Upstreaming the glibc Hurd port

  On Fri, 19 Jan 2018, Thomas Schwinge wrote:

> Hi Joseph!
> 
> On Fri, 19 Jan 2018 00:34:42 +0000, Joseph Myers <joseph@codesourcery.com> wrote:
> > On Fri, 19 Jan 2018, Samuel Thibault wrote:
> > 
> > > Joseph Myers, on jeu. 18 janv. 2018 23:15:59 +0000, wrote:
> > > > Thanks for the changes pushed to sthibaul/hurd-builds so far (I realise 
> > > > there will be more to get it into a buildable state, e.g. the actual 
> > > > libpthread implementation).
> > > 
> > > What I have pushed is basically only missing the libpthread
> > > implementation, so you already have an idea of the minimal set of
> > > modifications to get something building (and IIRC essentially passing
> > > the testsuite).
> > 
> > I'd still like to have the libpthread implementation there (with a view to 
> > seeing if I can get build-many-glibcs.py working for Hurd with this branch 
> 
> Many thanks for your offer!  As far as I'm aware indeed nobody from the
> Hurd team has spent time on that yet.

This patch adds build-many-glibcs.py support for GNU Hurd.  It is
intended for master, where the builds of the i686-gnu configuration
would fail until sufficient support is merged to master, so completing
build-many-glibcs.py coverage of all glibc ABIs and making results
accurately reflect the broken state of builds for Hurd.  Using
sthibaul/hurd-builds branch, it reaches the glibc build, which then
falls over with errors starting:

In file included from mutex-init.c:19:0:
../mach/lock-intern.h: In function '__spin_lock_init':
../mach/lock-intern.h:41:13: error: 'LLL_INITIALIZER' undeclared (first use in this function)
   *__lock = LLL_INITIALIZER;
             ^~~~~~~~~~~~~~~
../mach/lock-intern.h:41:13: note: each undeclared identifier is reported only once for each function it appears in
../mach/lock-intern.h: In function '__spin_lock':
../mach/lock-intern.h:50:3: error: implicit declaration of function 'lll_lock' [-Werror=implicit-function-declaration]
   lll_lock (__lock, 0);
   ^~~~~~~~
In file included from mutex-init.c:20:0:
../mach/lowlevellock.h: At top level:
../mach/lowlevellock.h:21:10: fatal error: mach/gnumach.h: No such file or directory
 #include <mach/gnumach.h>
          ^~~~~~~~~~~~~~~~

Could Hurd people review how this handles building for Hurd, and
indicate whether the above errors indicate problems with these
changes, or simply incompleteness of the build support on the
sthibaul/hurd-builds branch at present?

2018-01-19  Joseph Myers  <joseph@codesourcery.com>

	* scripts/build-many-glibcs.py (Context.add_all_configs): Add
	i686-gnu configurations.
	(Context.run_builds): Include mig, gnumach and hurd in components
	considered.
	(Context.checkout): Add mig, gnumach and hurd to components.
	(Context.checkout_tar): Add URL mappings for mig, gnumach and
	hurd.
	(Context.bot_cycle): Check for changes to mig, gnumach and hurd.
	(Config.build): Install gnumach headers, build mig and install
	hurd headers for 'gnu' OS.
	(Config.install_gnumach_headers): New function.
	(Config.install_hurd_headers): Likewise.
	(Glibc.build_glibc): Do not use /usr for 'gnu' OS.  Specifiy MIG
	when building for 'gnu' OS.
  

Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> or simply incompleteness of the build support on the
> sthibaul/hurd-builds branch at present?

It's still incomplete, yes.

Samuel
  

Incidentally, building for GNU/Linux (at least x86_64) is broken on the 
sthibaul/hurd-builds branch (I suspect, based on the error messages, that 
"t2.26/sched_param" was responsible, but didn't verify that).  (I was 
testing to make sure my build-many-glibcs.py changes didn't affect 
GNU/Linux builds and so are safe to apply to master.  Building for 
GNU/Linux is not of course a priority for the branch, but any such issues 
with changes to non-OS-specific code will need fixing for merging to 
master.)
  

Joseph Myers, on ven. 19 janv. 2018 17:50:19 +0000, wrote:
> Incidentally, building for GNU/Linux (at least x86_64) is broken on the 
> sthibaul/hurd-builds branch (I suspect, based on the error messages, that 
> "t2.26/sched_param" was responsible, but didn't verify that).

sched_param is very probably a culprit, yes.

Samuel
  

Hello,

Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> Could Hurd people review how this handles building for Hurd,

Yes, it looks good.

> and indicate whether the above errors indicate problems with these
> changes, or simply incompleteness of the build support on the
> sthibaul/hurd-builds branch at present?

They are not related to the changes.  I have pushed fix updates against
them.

There is just one missing thing: mig prototypes etc. are not perfect,
and we thus have some nasty warnings about void * vs const void *. We'd
have to use

         if self.os == 'gnu':
             cfg_cmd += ['MIG=%s' % self.tool_name('mig')]
+            cfg_cmd += ['--disable-werror']

for now until we fix that.

Samuel
  

On Wed, 24 Jan 2018, Samuel Thibault wrote:

> Hello,
> 
> Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> > Could Hurd people review how this handles building for Hurd,
> 
> Yes, it looks good.

Thanks, I've committed it to master.

> > and indicate whether the above errors indicate problems with these
> > changes, or simply incompleteness of the build support on the
> > sthibaul/hurd-builds branch at present?
> 
> They are not related to the changes.  I have pushed fix updates against
> them.

Now I see errors about missing libc-lockP.h, and "implicit declaration of 
function '__spin_lock_solid'", and the discarded qualifiers errors you 
note below.

> There is just one missing thing: mig prototypes etc. are not perfect,
> and we thus have some nasty warnings about void * vs const void *. We'd
> have to use
> 
>          if self.os == 'gnu':
>              cfg_cmd += ['MIG=%s' % self.tool_name('mig')]
> +            cfg_cmd += ['--disable-werror']
> 
> for now until we fix that.

A properly upstreamed port should not need --disable-werror.  If 
workarounds are needed until there's a fixed mig release (or whatever), 
they could take the form of explicit casts, or CFLAGS-<file> += 
-Wno-error=discarded-qualifiers - disabling a particular warning being an 
error in a particular file is much better than globally disabling all 
warnings as errors.  (Strictly -Wno-error=discarded-qualifiers shouldn't 
be used unconditionally since that warning option is new in GCC 5 and 
glibc supports building with GCC 4.9, but in the current state of the Hurd 
port I think we can ignore that in Hurd-specific Makefiles.)
  

Samuel Thibault, on mer. 24 janv. 2018 02:10:51 +0100, wrote:
> Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> > and indicate whether the above errors indicate problems with these
> > changes, or simply incompleteness of the build support on the
> > sthibaul/hurd-builds branch at present?
> 
> They are not related to the changes.  I have pushed fix updates against
> them.

The next error is about inclusion of libc-lockP.h.  That's where I'll
have to import libpthread.

Samuel
  

Samuel Thibault, on mer. 24 janv. 2018 02:27:26 +0100, wrote:
> Samuel Thibault, on mer. 24 janv. 2018 02:10:51 +0100, wrote:
> > Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> > > and indicate whether the above errors indicate problems with these
> > > changes, or simply incompleteness of the build support on the
> > > sthibaul/hurd-builds branch at present?
> > 
> > They are not related to the changes.  I have pushed fix updates against
> > them.
> 
> The next error is about inclusion of libc-lockP.h.  That's where I'll
> have to import libpthread.

Which I have now done.  I see that it now fails on missing reference to
__file_exec_paths.  That's indeed a new RPC which hasn't been released
yet, so we'd need to use a git snapshot.

Samuel
  

On Thu, 25 Jan 2018, Samuel Thibault wrote:

> Samuel Thibault, on mer. 24 janv. 2018 02:27:26 +0100, wrote:
> > Samuel Thibault, on mer. 24 janv. 2018 02:10:51 +0100, wrote:
> > > Joseph Myers, on ven. 19 janv. 2018 17:23:29 +0000, wrote:
> > > > and indicate whether the above errors indicate problems with these
> > > > changes, or simply incompleteness of the build support on the
> > > > sthibaul/hurd-builds branch at present?
> > > 
> > > They are not related to the changes.  I have pushed fix updates against
> > > them.
> > 
> > The next error is about inclusion of libc-lockP.h.  That's where I'll
> > have to import libpthread.
> 
> Which I have now done.  I see that it now fails on missing reference to
> __file_exec_paths.  That's indeed a new RPC which hasn't been released
> yet, so we'd need to use a git snapshot.

If a git version of Hurd (or some other component) is needed, it would be 
reasonable to make vcs-mainline the default version of Hurd until there's 
a new release.  Longer-term (once Hurd is working on master) I'd hope 
there would be a clear (and documented) notion of minimum compile-time and 
run-time Hurd versions, as there is for glibc using the Linux kernel, with 
any features of newer versions being used only conditionally, so that the 
most recent releases are generally sufficient to build and use glibc for 
Hurd.
  

Regarding the libpthread / htl code, and getting it ready for inclusion in 
glibc master:

Obviously my general coding style comments at 
<https://sourceware.org/ml/libc-alpha/2018-01/msg00646.html> apply equally 
to this code.  Apart from that:

* Remove htl/ChangeLog.  We don't have subdirectory ChangeLogs now.  
Everything goes in the top-level ChangeLog, with older ChangeLogs (that 
have actual ChangeLog content) being in the ChangeLog.old/ directory.  
When importing files / patches previously maintained elsewhere, I *do* 
think the ChangeLog header for those patches should name all authors who 
contributed to them (which may make for a long header with lots of authors 
listed).  (If the GNU Coding Standards change to stop requiring ChangeLog 
format and we decide to stop using it, we'll still need some convention 
for how to credit multi-author patches.)

* Remove htl/tests/.cvsignore.

* Support for building htl outside the glibc source tree (or with older 
glibc versions) should not be included.

* Files in htl/sysdeps should be moved into appropriate locations in the 
main sysdeps tree, just as was done with nptl/sysdeps when nptl ceased to 
be an add-on.

* You seem to have some custom system for building tests in htl/tests.  
Tests should be built and run using the normal glibc testsuite machinery 
(and should use <support/test-driver.c>).

* You have four installed non-bits/ API headers: pthread.h 
pthread/pthread.h pthread/pthreadtypes.h semaphore.h.  NPTL has just 
pthread.h and semaphore.h.  Do you really need pthread/pthread.h and 
pthread/pthreadtypes.h as installed public API headers?  I'd expect the 
same two API headers as NPTL has.

* The bits/ convention is for headers that are (a) installed, (b) only for 
use by other installed headers, not for direct inclusion by users (and 
sometimes have #error conditionals to guard against direct inclusion).  
Within that convention, there's a newer bits/types/ convention for headers 
defining a single type, which is intended as a replacement for the older 
__need_* convention.  Now, this brings up three points regarding the htl 
code (and possibly other pieces in the Hurd port).

(i) You still have some headers that define or use __need_*; those should 
be changed to use bits/types/ headers (__need_* has generally been 
eliminated from glibc, except where it's defined before including *GCC* 
headers, not glibc ones).

(ii) Some of the bits/ headers in htl look like they are just defining a 
single type, so should actually be bits/types/ headers named according to 
the new convention.

(iii) bits/memory.h and bits/pt-atomic.h don't appear to be installed 
headers, meaning they should not have bits/ names.  Actually, uses of 
those headers should probably be changed to use glibc's existing atomic.h 
interfaces, and those htl-specific headers removed - if for some reason 
the existing atomic.h interfaces are insufficient, maybe those interfaces 
need to be extended.


The following would be desirable cleanups, but maybe for after the code is 
in master:

* I'd expect that NPTL tests (and likewise HTL tests) are largely tests of 
POSIX (or GNU extension) threading functionality, not of features specific 
to one threading implementation.  Thus, they should as far as possible be 
shared between the different threading implementations.  I don't know the 
best directory arrangements for achieving that.

* Hopefully C11 threads support will be added for 2.28 (didn't get 
reviewed in time for 2.27).  The existing patches put it in the nptl/ 
directory, but again, to the extent that it actually builds on generic 
pthreads functionality, the code and its tests should be shared as much as 
possible between NPTL and HTL.

* Likewise for the pthread.h and semaphore.h API headers - only parts 
genuinely specific to a given implementation should be split out into 
implementation-specific bits/ headers.  (Indeed, the NPTL semaphore.h is 
already in sysdeps/pthread/ not an NPTL-specific directory - do you really 
need a different one for HTL?)
  

Joseph Myers, on jeu. 25 janv. 2018 16:12:48 +0000, wrote:
> do you really need [foo]

Assume no :)

I just imported the source as it is, containing everything that was
previously needed to make it buildable both within the hurd repository
and the glibc repository.

Thanks for listing the issues, though :)

Samuel
  

Hello,

Thanks a lot for the feedback on what needs to be done.  It was a busy
week-end :)

We should be almost there, I believe I had addressed in
sthibaul/hurd-builds all requirements except a few remaining bits:

- Two patches pending comments on libc-alpha:
  [PATCH] hurd: Initialize TLS and libpthread before signal thread start
  [PATCH] hurd: Fix early rtld access to errno

- plugging the htl tests to the glibc test infrastructure.

- Fixing GNU Coding Style, notably first line of files.

- Fixing the date in sysdeps/mach/hurd/bits/posix_opt.h.

Samuel
  

On Sun, Mar 18, 2018 at 9:51 PM, Samuel Thibault
<samuel.thibault@gnu.org> wrote:
> Hello,
>
> Thanks a lot for the feedback on what needs to be done.  It was a busy
> week-end :)
>
> We should be almost there, I believe I had addressed in
> sthibaul/hurd-builds all requirements except a few remaining bits:

Is it still expected that glibc trunk cannot be built in the
--host=i686-gnu configuration?  I am getting

In file included from ../include/link.h:52:0,
                 from ../include/dlfcn.h:4,
                 from ../sysdeps/generic/ldsodefs.h:32,
                 from ../sysdeps/i386/ldsodefs.h:39,
                 from ../sysdeps/gnu/ldsodefs.h:46,
                 from setup-thread.c:22:
../sysdeps/mach/libc-lock.h:227:11: fatal error: libc-lockP.h: No such
file or directory
 # include <libc-lockP.h>
           ^~~~~~~~~~~~~~
compilation terminated.

(I would like to suggest that getting "scripts/build-many-glibcs.py
$workdir compilers i686-gnu" to succeed, and
"scripts/build-many-glibcs.py $workdir glibcs i686-gnu" to fail only
in the testsuite phase, when $workdir/src/glibc contains a trunk
checkout, should be top priority -- once you get to that point, people
working on cross-cutting changes (like me) can ensure that they
haven't made the state of the Hurd port worse.)

zw
  

Zack Weinberg, on lun. 19 mars 2018 11:36:18 -0400, wrote:
> On Sun, Mar 18, 2018 at 9:51 PM, Samuel Thibault
> <samuel.thibault@gnu.org> wrote:
> > Hello,
> >
> > Thanks a lot for the feedback on what needs to be done.  It was a busy
> > week-end :)
> >
> > We should be almost there, I believe I had addressed in
> > sthibaul/hurd-builds all requirements except a few remaining bits:
> 
> Is it still expected that glibc trunk cannot be built in the
> --host=i686-gnu configuration?  I am getting

Are you using the sthibaul/hurd-builds branch?
There are still things missing in master, notably the htl/
directories.

> (I would like to suggest that getting "scripts/build-many-glibcs.py
> $workdir compilers i686-gnu" to succeed,

It does work on my system with the sthibaul/hurd-builds branch.

> when $workdir/src/glibc contains a trunk checkout, should be top
> priority

Sure, that's precisely my goal.  I'm just checking for things that might
look odd in the sthibaul/hurd-builds branch before I push them to
master.

Samuel
  

On Mon, Mar 19, 2018 at 11:46 AM, Samuel Thibault
<samuel.thibault@gnu.org> wrote:
> Zack Weinberg, on lun. 19 mars 2018 11:36:18 -0400, wrote:
>> On Sun, Mar 18, 2018 at 9:51 PM, Samuel Thibault
>> <samuel.thibault@gnu.org> wrote:
>> > Hello,
>> >
>> > Thanks a lot for the feedback on what needs to be done.  It was a busy
>> > week-end :)
>> >
>> > We should be almost there, I believe I had addressed in
>> > sthibaul/hurd-builds all requirements except a few remaining bits:
>>
>> Is it still expected that glibc trunk cannot be built in the
>> --host=i686-gnu configuration?  I am getting
>
> Are you using the sthibaul/hurd-builds branch?

No, that's what I meant by "glibc trunk".

> There are still things missing in master, notably the htl/
> directories.

Oh, OK.  No hurry.

zw
  

Zack Weinberg, on lun. 19 mars 2018 11:54:21 -0400, wrote:
> On Mon, Mar 19, 2018 at 11:46 AM, Samuel Thibault
> <samuel.thibault@gnu.org> wrote:
> > Zack Weinberg, on lun. 19 mars 2018 11:36:18 -0400, wrote:
> >> On Sun, Mar 18, 2018 at 9:51 PM, Samuel Thibault
> >> <samuel.thibault@gnu.org> wrote:
> >> > Hello,
> >> >
> >> > Thanks a lot for the feedback on what needs to be done.  It was a busy
> >> > week-end :)
> >> >
> >> > We should be almost there, I believe I had addressed in
> >> > sthibaul/hurd-builds all requirements except a few remaining bits:
> >>
> >> Is it still expected that glibc trunk cannot be built in the
> >> --host=i686-gnu configuration?  I am getting
> >
> > Are you using the sthibaul/hurd-builds branch?
> 
> No, that's what I meant by "glibc trunk".

Ok, sorry, I missed the "trunk" workd :)

Samuel
  

Hello Samuel,

19.03.2018 02:51 Samuel Thibault <samuel.thibault@gnu.org> wrote:
>
> Hello,
>
> Thanks a lot for the feedback on what needs to be done. It was a busy
> week-end :)

I appreciate your work. :-) Sorry for a kinda off-topic but could you
please visit the Patchwork site [1] and mark your committed patches
as committed, or ask someone to do it for you?  I'm asking in public
because there are lots of patches from other people as well, also this
makes a chance for someone to respond in case if I'm too overzealous.
Thank you.

Regards,

Rafal


[1] https://patchwork.sourceware.org/project/glibc/list/
  

Hello,

Rafal Luzynski, on mar. 27 mars 2018 01:13:23 +0200, wrote:
> I appreciate your work. :-) Sorry for a kinda off-topic but could you
> please visit the Patchwork site [1] and mark your committed patches
> as committed, or ask someone to do it for you?

Oh, I didn't know about it. Is there a way to make them marked as
commited right from the mail subject, for future commits?

Samuel
  

Rafal Luzynski, on mar. 27 mars 2018 01:13:23 +0200, wrote:
> 19.03.2018 02:51 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > Thanks a lot for the feedback on what needs to be done. It was a busy
> > week-end :)
> 
> I appreciate your work. :-) Sorry for a kinda off-topic but could you
> please visit the Patchwork site [1] and mark your committed patches
> as committed, or ask someone to do it for you?

It seems I can't mark patches submitted by other people, perhaps I just
need to be added to the "Maintainers" list?

Samuel
  

27.03.2018 09:45 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> [...]
> Oh, I didn't know about it. Is there a way to make them marked as
> commited right from the mail subject, for future commits?

I don't know. Any hints, anybody?


27.03.2018 11:00 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> [...]
> It seems I can't mark patches submitted by other people, perhaps I just
> need to be added to the "Maintainers" list?

No, I wouldn't ask you to mark patches by other people, if you mark
your own patches that would be a great cleaning work already.
When I mentioned other people I meant that other people should
do the same with their own patches, so that's a general message,
not just for you.

Regards,

Rafal
  

Rafal Luzynski, on mar. 27 mars 2018 12:40:27 +0200, wrote:
> 27.03.2018 11:00 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > [...]
> > It seems I can't mark patches submitted by other people, perhaps I just
> > need to be added to the "Maintainers" list?
> 
> No, I wouldn't ask you to mark patches by other people, if you mark
> your own patches that would be a great cleaning work already.

Just to be sure: I meant patches submitted by others which I have
commited myself to glibc.

Samuel
  

27.03.2018 12:43 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> Rafal Luzynski, on mar. 27 mars 2018 12:40:27 +0200, wrote:
> > 27.03.2018 11:00 Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > > [...]
> > > It seems I can't mark patches submitted by other people, perhaps I just
> > > need to be added to the "Maintainers" list?
> >
> > No, I wouldn't ask you to mark patches by other people, if you mark
> > your own patches that would be a great cleaning work already.
>
> Just to be sure: I meant patches submitted by others which I have
> commited myself to glibc.

That's only more confusing for me. I am a relatively new maintainer
here, this explains why it is so easy for me to put my attention on
the things I learned not so long ago. Regarding your questions we need
some feedback from more experienced maintainers, I am curious as well.

Regards,

Rafal
  

Samuel Thibault <samuel.thibault@gnu.org> writes:

> Rafal Luzynski, on mar. 27 mars 2018 01:13:23 +0200, wrote:
>> 19.03.2018 02:51 Samuel Thibault <samuel.thibault@gnu.org> wrote:
>> > Thanks a lot for the feedback on what needs to be done. It was a busy
>> > week-end :)
>> 
>> I appreciate your work. :-) Sorry for a kinda off-topic but could you
>> please visit the Patchwork site [1] and mark your committed patches
>> as committed, or ask someone to do it for you?
>
> It seems I can't mark patches submitted by other people, perhaps I just
> need to be added to the "Maintainers" list?

Indeed.

Carlos and Siddhesh, could you help Samuel?

For the record: Carlos and Siddhesh are the maintainers of our Patchwork
instance.
https://sourceware.org/glibc/wiki/MAINTAINERS#Maintainers_for_the_patchwork_instance

I can't put your account in the maintainers list, but I can change the status
of the patches.
Are these all the patches pending an update there?
https://patchwork.sourceware.org/project/glibc/list/?submitter=384
  

On 03/27/2018 09:46 AM, Tulio Magno Quites Machado Filho wrote:
> Samuel Thibault <samuel.thibault@gnu.org> writes:
> 
>> Rafal Luzynski, on mar. 27 mars 2018 01:13:23 +0200, wrote:
>>> 19.03.2018 02:51 Samuel Thibault <samuel.thibault@gnu.org> wrote:
>>>> Thanks a lot for the feedback on what needs to be done. It was a busy
>>>> week-end :)
>>>
>>> I appreciate your work. :-) Sorry for a kinda off-topic but could you
>>> please visit the Patchwork site [1] and mark your committed patches
>>> as committed, or ask someone to do it for you?
>>
>> It seems I can't mark patches submitted by other people, perhaps I just
>> need to be added to the "Maintainers" list?
> 
> Indeed.
> 
> Carlos and Siddhesh, could you help Samuel?

Fixed. I added Samuel to the maintainers list.

> For the record: Carlos and Siddhesh are the maintainers of our Patchwork
> instance.
> https://sourceware.org/glibc/wiki/MAINTAINERS#Maintainers_for_the_patchwork_instance
> 
> I can't put your account in the maintainers list, but I can change the status
> of the patches.
> Are these all the patches pending an update there?
> https://patchwork.sourceware.org/project/glibc/list/?submitter=384
  

Hello,

So, after various coding style fixes etc. I eventually pushed htl.

This means that build-glibcs i686-gnu now builds fine.  Among the
remaining TODOs, there are

- making testsuite pass
- fixing the generated errno file thing
- sharing tests between nptl and htl
- sharing pthread.h
- C11 threads


Concerning the testsuite, perhaps we could xfail the existing issues so
that build-glibcs i686-gnu succeeds?

Currently there are:

- header standard conformity issues: These will be hard to fix.
- elf/check-localplt: There will always be PLTs to libhurd/machuser.so
  anyway.
- elf/check-execstack: We have nested functions which make the stack
  executable indeed.
- check-abi-libmachuser, check-abi-libhurduser: These actually depend on
  .defs files in gnumach and hurd, so we can't really define ABI files.

Samuel
  

On 04/02/2018 02:10 AM, Samuel Thibault wrote:
> - elf/check-execstack: We have nested functions which make the stack
>    executable indeed.

I looked at the Hurd situation last month.  Hurd is always 
read-implies-exec, I think.  So there is no need to make the stacks 
executable, it does not have any observable effect on execution and 
therefore cannot be tested.

Thanks,
Florian
  

Florian Weimer, on lun. 02 avril 2018 09:51:00 +0200, wrote:
> On 04/02/2018 02:10 AM, Samuel Thibault wrote:
> > - elf/check-execstack: We have nested functions which make the stack
> >    executable indeed.
> 
> I looked at the Hurd situation last month.  Hurd is always
> read-implies-exec, I think.

Nobody has implemented NX in gnumach yet, but that doesn't mean nobody
will.

Samuel
  

On Mon, 2 Apr 2018, Samuel Thibault wrote:

> - header standard conformity issues: These will be hard to fix.

What are the issues here?

> - elf/check-localplt: There will always be PLTs to libhurd/machuser.so
>   anyway.

If a library has *local* PLT entries - PLT entries for within-library 
calls to other functions in that shared library - that are hard to fix to 
use hidden aliases, it's expected that the localplt.data files will list 
those as expected (with a "?" if the PLT entry may or may not be present 
depending on compiler version etc., as is the case for some configurations 
where functions get exported from both libgcc and glibc).

> - elf/check-execstack: We have nested functions which make the stack
>   executable indeed.

That's pointers to nested functions involving creation of trampolines?  
Do those nested functions actually improve the code or would it be cleaner 
(have cleaner internal interfaces etc.) without them?  Do all libraries 
have these or only some?

> - check-abi-libmachuser, check-abi-libhurduser: These actually depend on
>   .defs files in gnumach and hurd, so we can't really define ABI files.

Depend in what way?  Are you saying they export different symbols 
depending on the versions of gnumach and hurd glibc is built with?  How 
are symbol versions for such extra symbols determined - based on gnumach 
and hurd versions instead of glibc versions?

It's clearly desirable to be able to make sure that old symbol versions 
don't change.  But if the contents of those versions are determined by 
gnumach and hurd, maybe those packages need to install ABI baselines for 
the glibc tests (or something like that).

The nearest analogue I see in glibc for systems using the Linux kernel 
(without more information on how the gnumach/hurd dependency works) is the 
syscall lists - where we have a list in glibc of all possible syscall 
names (sysdeps/unix/sysv/linux/syscall-names.list), and a test will fail 
if the kernel has additional syscalls and is not newer than the version 
listed in that list (so using a different kernel version does not result 
in test failures, but the test is fully effective if the listed kernel 
version or an older kernel version is used).
  

On Mon, 2 Apr 2018, Samuel Thibault wrote:

> This means that build-glibcs i686-gnu now builds fine.  Among the
> remaining TODOs, there are

Thanks!  I'd add: the "requires out-of-tree patches" statement in README 
needs to be removed, and a NEWS entry is needed.  Will you be able to 
provide full execution test results for the testsuite on the per-release 
wiki pages for 2.28 and later releases, during each release freeze period?
  

Hello,

Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> 
> > This means that build-glibcs i686-gnu now builds fine.  Among the
> > remaining TODOs, there are
> 
> Thanks!  I'd add: the "requires out-of-tree patches" statement in README 
> needs to be removed,

Oh, I was unaware of that mention.

> and a NEWS entry is needed.

Right :)

> Will you be able to provide full execution test results for the
> testsuite on the per-release wiki pages for 2.28 and later releases,
> during each release freeze period?

Now that it does build and run quite fine, sure! :)

Samuel
  

Joseph Myers, on lun. 02 avril 2018 14:17:38 +0000, wrote:
> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> 
> > - header standard conformity issues: These will be hard to fix.
> 
> What are the issues here?

Some of these are small, like ./bits/types/sigevent_t.h's
sigev_notify_attributes not being pthread_attr_t*

Others need some work, like the missing SA_SIGINFO, for which we have
patches which need polishing and committing.

Others need implementing, like SA_NOCLDWAIT.

Others just need defining, like IUCLC, IXANY, etc.

There are a few remaining namespace issues due to missing __ marking or
spurious #includes.

So those, we can fix them.


Others really pose problem, like ./sysdeps/mach/hurd/bits/fcntl.h's
l_type/l_whence being int instead of short.

There is also sys/un.h which defines a sun_len field, which IIRC is to
be expected on BSD systems, but not defined in Posix?

Also, ioctl takes (int, unsigned long int, ...) but
./conform/XPG42/stropts.h/conform.out wants (int, int, ...)?

> > - elf/check-localplt: There will always be PLTs to libhurd/machuser.so
> >   anyway.
> 
> If a library has *local* PLT entries -

Ah.  I got confused by the presence of __vm_allocate which is an RPC,
but we actually have a non-RPC version inside libc.so itself.  There are
a hundred of them mostly in libc.so, ld.so, libpthread.so

> PLT entries for within-library calls to other functions in that shared
> library - that are hard to fix to use hidden aliases, it's expected
> that the localplt.data files will list those as expected

Ok.

> > - elf/check-execstack: We have nested functions which make the stack
> >   executable indeed.
> 
> That's pointers to nested functions involving creation of trampolines?  

Yes.

> Do those nested functions actually improve the code

Yes.  There are notably callbacks whose parameters don't permit to get
the context parameters etc.

>  Do all libraries have these or only some?

Only libc.so, ld.so and libpthread.so have them.

> > - check-abi-libmachuser, check-abi-libhurduser: These actually depend on
> >   .defs files in gnumach and hurd, so we can't really define ABI files.
> 
> Depend in what way?  Are you saying they export different symbols 
> depending on the versions of gnumach and hurd glibc is built with?

That is it, yes.

> How are symbol versions for such extra symbols determined - based on
> gnumach and hurd versions instead of glibc versions?

That was not actually settled, but I guess it should be gnumach and hurd
versions.

> maybe those packages need to install ABI baselines for the glibc tests
> (or something like that).

Indeed.

Samuel
  

On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> Hello,
>
> Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
>> On Mon, 2 Apr 2018, Samuel Thibault wrote:
>>
>> > This means that build-glibcs i686-gnu now builds fine.  Among the
>> > remaining TODOs, there are
>>
>> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
>> needs to be removed,
>
> Oh, I was unaware of that mention.
>
>

mig master branch failed to build on Fedora 27:

gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
parser.o routine.o server.o statement.o string.o type.o user.o utils.o
vprint.o
/usr/local/bin/ld: lexxer.o: in function `yylex':
/export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
undefined reference to `yywrap'
collect2: error: ld returned 1 exit status
make[3]: *** [Makefile:495: migcom] Error 1


H.J.
  

Samuel Thibault, on lun. 02 avril 2018 17:50:17 +0200, wrote:
> There are a few remaining namespace issues due to missing __ marking or
> spurious #includes.

One issue is with struct sched_param.  The __sched_param definition
was removed in glibc while htl's pthread_attr uses it.  For now I just
made struct___pthread_attr.h include <sched.h> but that brings things
unwanted for <sys/types.h> (which is supposed to pull pthread_attr).

So I guess we should revert to defining __sched_param?

Samuel
  

H.J. Lu, on lun. 02 avril 2018 09:01:30 -0700, wrote:
> On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > Hello,
> >
> > Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
> >> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> >>
> >> > This means that build-glibcs i686-gnu now builds fine.  Among the
> >> > remaining TODOs, there are
> >>
> >> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
> >> needs to be removed,
> >
> > Oh, I was unaware of that mention.
> 
> mig master branch failed to build on Fedora 27:
> 
> gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
> parser.o routine.o server.o statement.o string.o type.o user.o utils.o
> vprint.o
> /usr/local/bin/ld: lexxer.o: in function `yylex':
> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
> undefined reference to `yywrap'

Could you post config.log?  configure is supposed to detect this:

checking lex library... -lfl

Samuel
  

On Mon, Apr 2, 2018 at 9:16 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> H.J. Lu, on lun. 02 avril 2018 09:01:30 -0700, wrote:
>> On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
>> > Hello,
>> >
>> > Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
>> >> On Mon, 2 Apr 2018, Samuel Thibault wrote:
>> >>
>> >> > This means that build-glibcs i686-gnu now builds fine.  Among the
>> >> > remaining TODOs, there are
>> >>
>> >> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
>> >> needs to be removed,
>> >
>> > Oh, I was unaware of that mention.
>>
>> mig master branch failed to build on Fedora 27:
>>
>> gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
>> parser.o routine.o server.o statement.o string.o type.o user.o utils.o
>> vprint.o
>> /usr/local/bin/ld: lexxer.o: in function `yylex':
>> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
>> undefined reference to `yywrap'
>
> Could you post config.log?  configure is supposed to detect this:
>
> checking lex library... -lfl
>

checking lex library... none needed
  

H.J. Lu, on lun. 02 avril 2018 10:06:14 -0700, wrote:
> On Mon, Apr 2, 2018 at 9:16 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > H.J. Lu, on lun. 02 avril 2018 09:01:30 -0700, wrote:
> >> On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> >> > Hello,
> >> >
> >> > Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
> >> >> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> >> >>
> >> >> > This means that build-glibcs i686-gnu now builds fine.  Among the
> >> >> > remaining TODOs, there are
> >> >>
> >> >> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
> >> >> needs to be removed,
> >> >
> >> > Oh, I was unaware of that mention.
> >>
> >> mig master branch failed to build on Fedora 27:
> >>
> >> gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
> >> parser.o routine.o server.o statement.o string.o type.o user.o utils.o
> >> vprint.o
> >> /usr/local/bin/ld: lexxer.o: in function `yylex':
> >> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
> >> undefined reference to `yywrap'
> >
> > Could you post config.log?  configure is supposed to detect this:
> >
> > checking lex library... -lfl
> 
> checking lex library... none needed

Please really config.log, not only the configure output.

Samuel
  

On Mon, Apr 2, 2018 at 10:15 AM, Samuel Thibault
<samuel.thibault@gnu.org> wrote:
> H.J. Lu, on lun. 02 avril 2018 10:06:14 -0700, wrote:
>> On Mon, Apr 2, 2018 at 9:16 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
>> > H.J. Lu, on lun. 02 avril 2018 09:01:30 -0700, wrote:
>> >> On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
>> >> > Hello,
>> >> >
>> >> > Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
>> >> >> On Mon, 2 Apr 2018, Samuel Thibault wrote:
>> >> >>
>> >> >> > This means that build-glibcs i686-gnu now builds fine.  Among the
>> >> >> > remaining TODOs, there are
>> >> >>
>> >> >> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
>> >> >> needs to be removed,
>> >> >
>> >> > Oh, I was unaware of that mention.
>> >>
>> >> mig master branch failed to build on Fedora 27:
>> >>
>> >> gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
>> >> parser.o routine.o server.o statement.o string.o type.o user.o utils.o
>> >> vprint.o
>> >> /usr/local/bin/ld: lexxer.o: in function `yylex':
>> >> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
>> >> undefined reference to `yywrap'
>> >
>> > Could you post config.log?  configure is supposed to detect this:
>> >
>> > checking lex library... -lfl
>>
>> checking lex library... none needed
>
> Please really config.log, not only the configure output.
>

configure:4096: checking lex library
configure:4110: gcc -o conftest -g -O2   conftest.c   >&5
/usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `input':
/export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:1185:
undefined reference to `yywrap'
/usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `yylex':
/export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:879:
undefined reference to `yywrap'
/usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `main':
/export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/conftest.l:18:
undefined reference to `yywrap'
collect2: error: ld returned 1 exit status
configure:4110: $? = 1
....
configure:4460: result: no
...
configure: exit 0
  

H.J. Lu, on lun. 02 avril 2018 10:22:31 -0700, wrote:
> On Mon, Apr 2, 2018 at 10:15 AM, Samuel Thibault
> <samuel.thibault@gnu.org> wrote:
> > H.J. Lu, on lun. 02 avril 2018 10:06:14 -0700, wrote:
> >> On Mon, Apr 2, 2018 at 9:16 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> >> > H.J. Lu, on lun. 02 avril 2018 09:01:30 -0700, wrote:
> >> >> On Mon, Apr 2, 2018 at 7:47 AM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> >> >> > Hello,
> >> >> >
> >> >> > Joseph Myers, on lun. 02 avril 2018 14:22:28 +0000, wrote:
> >> >> >> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> >> >> >>
> >> >> >> > This means that build-glibcs i686-gnu now builds fine.  Among the
> >> >> >> > remaining TODOs, there are
> >> >> >>
> >> >> >> Thanks!  I'd add: the "requires out-of-tree patches" statement in README
> >> >> >> needs to be removed,
> >> >> >
> >> >> > Oh, I was unaware of that mention.
> >> >>
> >> >> mig master branch failed to build on Fedora 27:
> >> >>
> >> >> gcc  -g -O2   -o migcom error.o global.o header.o lexxer.o migcom.o
> >> >> parser.o routine.o server.o statement.o string.o type.o user.o utils.o
> >> >> vprint.o
> >> >> /usr/local/bin/ld: lexxer.o: in function `yylex':
> >> >> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lexxer.c:1834:
> >> >> undefined reference to `yywrap'
> >> >
> >> > Could you post config.log?  configure is supposed to detect this:
> >> >
> >> > checking lex library... -lfl
> >>
> >> checking lex library... none needed
> >
> > Please really config.log, not only the configure output.
> >
> 
> configure:4096: checking lex library
> configure:4110: gcc -o conftest -g -O2   conftest.c   >&5
> /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `input':
> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:1185:
> undefined reference to `yywrap'
> /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `yylex':
> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:879:
> undefined reference to `yywrap'
> /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `main':
> /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/conftest.l:18:
> undefined reference to `yywrap'
> collect2: error: ld returned 1 exit status
> configure:4110: $? = 1
> ....
> configure:4460: result: no

Please really post config.log (or send it privately). "result: no" here
is not related to "checking lex library".

Samuel
  

Samuel Thibault, on lun. 02 avril 2018 19:35:11 +0200, wrote:
> > configure:4096: checking lex library
> > configure:4110: gcc -o conftest -g -O2   conftest.c   >&5
> > /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `input':
> > /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:1185:
> > undefined reference to `yywrap'
> > /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `yylex':
> > /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/lex.yy.c:879:
> > undefined reference to `yywrap'
> > /usr/local/bin/ld: /tmp/ccDAnO2r.o: in function `main':
> > /export/gnu/import/git/toolchain/build/compilers/i686-gnu/mig/conftest.l:18:
> > undefined reference to `yywrap'
> > collect2: error: ld returned 1 exit status
> > configure:4110: $? = 1
> > ....
> > configure:4460: result: no
> 
> Please really post config.log (or send it privately). "result: no" here
> is not related to "checking lex library".

I guess you don't have libfl-devel on your system, and apparently
autoconf's programs.m4 doesn't actually handle that case.

Samuel
  

On Mon, 2 Apr 2018, Samuel Thibault wrote:

> Others really pose problem, like ./sysdeps/mach/hurd/bits/fcntl.h's
> l_type/l_whence being int instead of short.

Where something is problematic to fix, because a fix would break the ABI 
or needs some external feature, there is an xfail mechanism internal to 
the conform tests.  It involves a bug being filed in Bugzilla for the 
issue in question, an addition to conformtest-xfail-conds (conditional on 
ifeq ($(subdir),conform)) in an appropriate sysdeps Makefile, with a 
comment referencing the bug, and xfail[cond]- on the relevant expectation 
in the relevant -data file, again with a comment referencing the bug.  
For example:

// Bug 17786: st_dev has wrong type.
xfail[mips-o32-linux]-element {struct stat} dev_t st_dev

Before doing any such XFAILing, you should check that the expectation is 
actually backed up by the relevant standard and that a fix really does 
need an ABI change or a new feature.  Also, this XFAIL mechanism can only 
be used for positive expectations that are failing - it can't be used for 
cases where the header violates the expected namespace.

> There is also sys/un.h which defines a sun_len field, which IIRC is to
> be expected on BSD systems, but not defined in Posix?

Well, in fact POSIX reserves sun_* for sys/un.h (note the reservations are 
in a separate part of the standard from the main definitions of header 
contents), so there's a bug in the expectations not allowing for it.  This 
illustrates the need for checking such failures against the standards to 
see where the bug is.

> Also, ioctl takes (int, unsigned long int, ...) but
> ./conform/XPG42/stropts.h/conform.out wants (int, int, ...)?

That's already generically XFAILed with reference to bug 14362.

> > Do those nested functions actually improve the code
> 
> Yes.  There are notably callbacks whose parameters don't permit to get
> the context parameters etc.
> 
> >  Do all libraries have these or only some?
> 
> Only libc.so, ld.so and libpthread.so have them.

Then maybe some mechanism is needed for sysdeps Makefiles to define 
libraries expected to have executable stacks.
  

On Mon, 2 Apr 2018, Samuel Thibault wrote:

> Samuel Thibault, on lun. 02 avril 2018 17:50:17 +0200, wrote:
> > There are a few remaining namespace issues due to missing __ marking or
> > spurious #includes.
> 
> One issue is with struct sched_param.  The __sched_param definition
> was removed in glibc while htl's pthread_attr uses it.  For now I just
> made struct___pthread_attr.h include <sched.h> but that brings things
> unwanted for <sys/types.h> (which is supposed to pull pthread_attr).
> 
> So I guess we should revert to defining __sched_param?

If you need, on Hurd, in installed headers, a type "struct __sched_param", 
that would most naturally go in a Hurd-specific 
bits/types/struct___sched_param.h.  If that's not appropriate, please 
explain the issue in more detail.  Anything restoring the old __need_* 
mechanism for any glibc-internal definitions is not appropriate (struct 
__sched_param was removed as part of removing __need_*).
  

On Mon, 2 Apr 2018, Samuel Thibault wrote:

> This means that build-glibcs i686-gnu now builds fine.  Among the
> remaining TODOs, there are

If you use mainline GCC, however, it fails:

../sysdeps/mach/hurd/if_index.c: In function '__if_nametoindex':
../sysdeps/mach/hurd/if_index.c:40:3: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
   strncpy (ifr.ifr_name, ifname, IFNAMSIZ);
   ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  

Joseph Myers, on mar. 03 avril 2018 15:45:13 +0000, wrote:
> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> 
> > This means that build-glibcs i686-gnu now builds fine.  Among the
> > remaining TODOs, there are
> 
> If you use mainline GCC, however, it fails:
> 
> ../sysdeps/mach/hurd/if_index.c: In function '__if_nametoindex':
> ../sysdeps/mach/hurd/if_index.c:40:3: error: 'strncpy' specified bound 16 equals destination size [-Werror=stringop-truncation]
>    strncpy (ifr.ifr_name, ifname, IFNAMSIZ);
>    ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Oh, a real bug indeed :)

Samuel
  

The build for i686-gnu also fails using GCC 6 branch with 
build-many-glibcs.py:

hurdsig.c: In function 'interrupted_reply_port_location.isra.1':
hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
   *(volatile mach_port_t *) portloc = *portloc;
                                       ^~~~~~~~

I haven't investigated whether this warning is valid, or whether it's 
bogus (in which case we don't add initializations just to fix warnings, 
but may used DIAG_*_NEEDS_COMMENT with appropriate explanations of what 
warning appears and why it is bogus).
  

Joseph Myers, on mar. 03 avril 2018 21:48:32 +0000, wrote:
> The build for i686-gnu also fails using GCC 6 branch with 
> build-many-glibcs.py:
> 
> hurdsig.c: In function 'interrupted_reply_port_location.isra.1':
> hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>    *(volatile mach_port_t *) portloc = *portloc;
>                                        ^~~~~~~~
> 
> I haven't investigated whether this warning is valid, or whether it's 
> bogus

Well, it's completely bogus: portloc is initialized just above. I don't
understand why it wouldn't see that.

Samuel
  

On Tue, Apr 3, 2018 at 5:58 PM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> Joseph Myers, on mar. 03 avril 2018 21:48:32 +0000, wrote:
>> The build for i686-gnu also fails using GCC 6 branch with
>> build-many-glibcs.py:
>>
>> hurdsig.c: In function 'interrupted_reply_port_location.isra.1':
>> hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>    *(volatile mach_port_t *) portloc = *portloc;
>>                                        ^~~~~~~~
>>
>> I haven't investigated whether this warning is valid, or whether it's
>> bogus
>
> Well, it's completely bogus: portloc is initialized just above. I don't
> understand why it wouldn't see that.

I think it thinks the *value pointed-to by portloc* is uninitialized.
Writing that value to a volatile memory location (which happens to be
the same memory location, but you specifically told it not to pay
attention to that with the volatile cast) is therefore invalid.

I don't know this code well enough to suggest what you might could do
about that.  Since the warning does not happen with GCC 7 or 8 I would
be fine with suppressing the diagnostic.

zw
  

On Tue, 3 Apr 2018, Zack Weinberg wrote:

> On Tue, Apr 3, 2018 at 5:58 PM, Samuel Thibault <samuel.thibault@gnu.org> wrote:
> > Joseph Myers, on mar. 03 avril 2018 21:48:32 +0000, wrote:
> >> The build for i686-gnu also fails using GCC 6 branch with
> >> build-many-glibcs.py:
> >>
> >> hurdsig.c: In function 'interrupted_reply_port_location.isra.1':
> >> hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >>    *(volatile mach_port_t *) portloc = *portloc;
> >>                                        ^~~~~~~~
> >>
> >> I haven't investigated whether this warning is valid, or whether it's
> >> bogus
> >
> > Well, it's completely bogus: portloc is initialized just above. I don't
> > understand why it wouldn't see that.
> 
> I think it thinks the *value pointed-to by portloc* is uninitialized.

This is just after a call to _hurdsig_catch_memory_fault, which is a macro 
involving a call to setjmp.  I think the returns-twice nature of setjmp is 
confusing the compiler into thinking portloc itself is uninitialized (I 
don't know why this particular warning) - in fact, the second return of 
setjmp will never reach the code getting the warning (as setjmp will 
return nonzero, so _hurdsig_catch_memory_fault will).
  

On 04/03/2018 11:58 PM, Samuel Thibault wrote:
> Joseph Myers, on mar. 03 avril 2018 21:48:32 +0000, wrote:
>> The build for i686-gnu also fails using GCC 6 branch with
>> build-many-glibcs.py:
>>
>> hurdsig.c: In function 'interrupted_reply_port_location.isra.1':
>> hurdsig.c:250:39: error: 'portloc' may be used uninitialized in this function [-Werror=maybe-uninitialized]
>>     *(volatile mach_port_t *) portloc = *portloc;
>>                                         ^~~~~~~~
>>
>> I haven't investigated whether this warning is valid, or whether it's
>> bogus
> 
> Well, it's completely bogus: portloc is initialized just above. I don't
> understand why it wouldn't see that.

You will have to look at the GIMPLE or assembler to determine if the 
warning is bogus after GCC has processed the setjmp call.  It may very 
well be the case that after those transformations, there *is* an 
uninitialized use of portloc.

Suppressing the warning could be the wrong thing to do here.  You may 
have to declare portloc itself volatile.

Thanks a lot for all these Hurd changes, by the way.  I really 
appreciate your work.

Thanks,
Florian
  

Joseph Myers, le mar. 03 avril 2018 00:10:30 +0000, a ecrit:
> On Mon, 2 Apr 2018, Samuel Thibault wrote:
> > Others really pose problem, like ./sysdeps/mach/hurd/bits/fcntl.h's
> > l_type/l_whence being int instead of short.
> 
> Where something is problematic to fix, because a fix would break the ABI 
> or needs some external feature, there is an xfail mechanism internal to 
> the conform tests.

Ok, thanks for the info, I could work it out :)

There are some ABI-compatible changes which can be made.  One of them is
struct shmid_ds's shm_segsz which is int but should be size_t.  That is
defined as int in both ./sysvipc/sys/shm.h and ./sysdeps/gnu/bits/shm.h.
I have checked that the kfreebsd port uses its own shm.h that defines it
to size_t.  I'd tend to think that we do not have any 64bit port using
./sysvipc/sys/shm.h or ./sysdeps/gnu/bits/shm.h, and thus we can just
fix them into size_t since on 32bit ports it is ABI-compatible with int?
(except the bitness, but I guess it does not problems in practice?)

Samuel
  

Hello,

Samuel Thibault, le jeu. 19 avril 2018 01:57:49 +0200, a ecrit:
> I'd tend to think that we do not have any 64bit port using
> ./sysvipc/sys/shm.h
(I meant include/bits/shm.h here)
> or ./sysdeps/gnu/bits/shm.h, and thus we can just fix them into size_t
> since on 32bit ports it is ABI-compatible with int? (except the
> bitness, but I guess it does not problems in practice?)

ping?
(Linux has its own bits/shm.h, the kfreebsd port has its own bits/shm.h)

Samuel