[2/2] gdb/doc: describe x87 registers

  While investigating this [1], I initially had no idea what register
"fioff" stood for, making it difficult to map it to something in the
Intel or AMD manuals.  Similarly, I can imaging someone familiar with
x87 to want to print the "x87 last instruction address", and have no
clue that GDB makes it available as register "fioff".  The names of the
x87 state fields don't seem to be standardized, they even change between
sections of the Intel manual (between the FSAVE, FXSAVE and XSAVE area
descriptions).

Add some details to the doc to help one map GDB register names to x87
state fields.

[1] https://inbox.sourceware.org/gdb-patches/20230908022722.430741-1-simon.marchi@efficios.com/T/#u

Change-Id: I0ea1eb648358e62da4aa87eea3515ee8a09f2762
---
 gdb/doc/gdb.texinfo | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
  

> Cc: Simon Marchi <simon.marchi@efficios.com>
> Date: Fri,  8 Sep 2023 11:20:58 -0400
> From: Simon Marchi via Gdb-patches <gdb-patches@sourceware.org>
> 
> While investigating this [1], I initially had no idea what register
> "fioff" stood for, making it difficult to map it to something in the
> Intel or AMD manuals.  Similarly, I can imaging someone familiar with
> x87 to want to print the "x87 last instruction address", and have no
> clue that GDB makes it available as register "fioff".  The names of the
> x87 state fields don't seem to be standardized, they even change between
> sections of the Intel manual (between the FSAVE, FXSAVE and XSAVE area
> descriptions).
> 
> Add some details to the doc to help one map GDB register names to x87
> state fields.
> 
> [1] https://inbox.sourceware.org/gdb-patches/20230908022722.430741-1-simon.marchi@efficios.com/T/#u
> 
> Change-Id: I0ea1eb648358e62da4aa87eea3515ee8a09f2762
> ---
>  gdb/doc/gdb.texinfo | 19 +++++++++++++++++++
>  1 file changed, 19 insertions(+)

Thanks, such additions are always welcome.

Approved-By: Eli Zaretskii <eliz@gnu.org>
  

On 2023-09-08 16:20, Simon Marchi via Gdb-patches wrote:
> While investigating this [1], I initially had no idea what register
> "fioff" stood for, making it difficult to map it to something in the
> Intel or AMD manuals.  Similarly, I can imaging someone familiar with
> x87 to want to print the "x87 last instruction address", and have no
> clue that GDB makes it available as register "fioff".  The names of the
> x87 state fields don't seem to be standardized, they even change between
> sections of the Intel manual (between the FSAVE, FXSAVE and XSAVE area
> descriptions).
> 
> Add some details to the doc to help one map GDB register names to x87
> state fields.
> 

Thanks for implementing this!  Just one nit below:

> +@subsubsection x87 registers
> +
> +GDB provides access to the x87 state through the following registers:

GDB -> @value{GDBN}
  

On 9/8/23 13:03, Pedro Alves wrote:
> On 2023-09-08 16:20, Simon Marchi via Gdb-patches wrote:
>> While investigating this [1], I initially had no idea what register
>> "fioff" stood for, making it difficult to map it to something in the
>> Intel or AMD manuals.  Similarly, I can imaging someone familiar with
>> x87 to want to print the "x87 last instruction address", and have no
>> clue that GDB makes it available as register "fioff".  The names of the
>> x87 state fields don't seem to be standardized, they even change between
>> sections of the Intel manual (between the FSAVE, FXSAVE and XSAVE area
>> descriptions).
>>
>> Add some details to the doc to help one map GDB register names to x87
>> state fields.
>>
> 
> Thanks for implementing this!  Just one nit below:
> 
>> +@subsubsection x87 registers
>> +
>> +GDB provides access to the x87 state through the following registers:
> 
> GDB -> @value{GDBN}
> 

Thanks, fixed and pushed.

Simon