Re: PATCH: Add functions to write core notes for i386/amd64

["H.J. Lu" <hjl dot tools at gmail dot com>]

On Mon, Apr 19, 2010 at 10:56 AM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>> Date: Mon, 19 Apr 2010 09:20:11 -0700
>> From: "H.J. Lu" <hjl.tools@gmail.com>
>>
>> On Mon, Apr 19, 2010 at 9:03 AM, Mark Kettenis <mark.kettenis@xs4all.nl> wrote:
>> > This adds the necessary backend functions to write proper core notes
>> > like the ppc code already has. ?This is necessary for GDB to generate
>> > proper 32-bit core dumps on 64-bit systems.
>> > ok?
>> >
>> >
>> > 2010-04-19 ?Mark Kettenis ?<kettenis@gnu.org>
>> >
>> > ? ? ? ?* elf64-x86-64.c (elf64_x86_64_write_core_note): New function.
>> > ? ? ? ?(elf_backend_write_core_note): Define.
>> > ? ? ? ?* elf32-i386.c (elf_i386_write_core_note): New function.
>> > ? ? ? ?(elf_backend_write_core_note): Define.
>> >
>>
>> It is not OK. I am not sure if it will work for Linux since Linux has
>> different note sizes.
>
> Where do you think I tested this code?
>
>> In any case, after
>>
>> http://sourceware.org/ml/binutils/2010-04/msg00131.html
>>
>> NT_PRPSINFO and NT_PRSTATUS should work fine on
>> Linux/x86-64.
>
> No, currently GDB writes out bogus notes for 32-bit core dumps on
> Linux/amd64 systems.

Changing elf64-x86-64.c alone won't fix it. Have you tried your
GDB fix without changing elf64-x86-64.c?

>> I think the proper way to fix it is to define PRPSINFO32_T and
>> PRPSINFO32_T for your x86-64 hosts.
>
> The long term plan in GDB is to make it possible to generate core
> dumps even on non-native configurations. ?In order to do that, it is
> necessary to add these functions that write out the proper core notes
> without depending on any host-specific header files.
>

I thought about it. In theory, it is possible since GDB does have all
register info. I think reading core is OK today. Writing core is a problem.
I'd like to see the complete patch for non-native gcore. We may
need to adjust BFD interface to support it.

Thanks.

-- 
H.J.