[PATCHv2 2/9] bfd/binutils: support for gdb target descriptions in the core file

[Strasuns, Mihails]

> -----Original Message-----
> From: Gdb-patches <gdb-patches-bounces@sourceware.org> On Behalf Of
> Andrew Burgess
> Sent: Wednesday, January 20, 2021 9:23 PM
> To: gdb-patches@sourceware.org; binutils@sourceware.org
> Cc: Fredrik Hederstierna <fredrik@hederstierna.com>
> Subject: [PATCHv2 2/9] bfd/binutils: support for gdb target descriptions in
> the core file
> 
> This commit lays the ground work for allowing GDB to write its target
> description into a generated core file.
> 
> The goal of this work is to allow a user to connect to a remote target, capture
> a core file from within GDB, then pass the executable and core file to another
> user and have the user be able to examine the state of the machine without
> needing to connect to a running target.
>
> Different remote targets can have different register sets and this information
> is communicated from the target to GDB in the target description.

Why is it necessary to store a GDB target description for this? Core files already define machine/arch, same as executable ELFs. There still can be some register variation between different platform versions, but it would still need to be denoted somehow in a native core file.

My concern is for making a "GDB core file" and a "native core file" even more different than it is currently on Linux. I guess this is aimed at a barebone environments where there is currently no native core dump support at all but even there it is not guaranteed.
 
> It is possible for a user to extract the target description from GDB and pass
> this along with the core file so that when the core file is used the target
> description can be fed back into GDB, however this is not a great user
> experience.
> 
> It would be nicer, I think, if GDB could write the target description directly
> into the core file, and then make use of this description when loading a core
> file.
> 
> This commit performs the binutils/bfd side of this task, adding the boiler
> plate functions to access the target description from within a core file note,
> and reserving a new number for a note containing the target description.
> 
> Later commits will extend GDB to make use of this.
Intel Deutschland GmbH
Registered Address: Am Campeon 10-12, 85579 Neubiberg, Germany
Tel: +49 89 99 8853-0, www.intel.de
Managing Directors: Christin Eisenschmid, Gary Kershaw
Chairperson of the Supervisory Board: Nicole Lau
Registered Office: Munich
Commercial Register: Amtsgericht Muenchen HRB 186928