Date: Mon, 2 Apr 2001 14:17:10 +0400
From: egor duda <deo AT logos-m DOT ru>
X-Mailer: The Bat! (v1.45) Personal
Organization: deo
X-Priority: 3 (Normal)
Message-ID: <923311812.20010402141710@logos-m.ru>
To: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
CC: gdb AT sources DOT redhat DOT com, sandmann AT clio DOT rice DOT edu, djgpp-workers AT delorie DOT com
Subject: Re: Adding support for core files to DJGPP
In-reply-To: <200104020813.KAA27119@is.elta.co.il>
References: <200103300906 DOT EAA18026 AT indy DOT delorie DOT com>
 <12289438285 DOT 20010330142921 AT logos-m DOT ru> <200104020813 DOT KAA27119 AT is DOT elta DOT co DOT il>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Reply-To: djgpp-workers AT delorie DOT com
Errors-To: nobody AT delorie DOT com
X-Mailing-List: djgpp-workers AT delorie DOT com
X-Unsubscribes-To: listserv AT delorie DOT com
Precedence: bulk

Hi!

Monday, 02 April, 2001 Eli Zaretskii eliz AT is DOT elta DOT co DOT il wrote:

>> all committed pages in process address space are written to .mem
>> sections

EZ> I don't see .mem sections mentioned anywhere in the SysV ABI documents
EZ> available from http://www.sco.com/developer/devspecs/.  Did I miss
EZ> something?  Is there any other documentation about ELF available
EZ> somewhere, where these sections are documented?

i think ".mem/" sections is just a common convention gdb supports. System V
ABI specification explicitly says
(at http://www.sco.com/developer/gabi/latest/ch4.eheader.html)
"Although the core file contents are unspecified, type ET_CORE is reserved to
mark the file."

so i suppose the best way is to use the gdb and/or cygwin's dumper sources.
actually, all you have to do is

          sprintf (sect_name, ".mem/%u", sect_no);
          sect_flags = SEC_HAS_CONTENTS | SEC_ALLOC | SEC_LOAD;
          sect_size = memory_block_size;
          sect_vma = (bfd_vma) (memory_block_base_address);

and then write memory region contents to section via bfd_set_section_contents ().

>> winsup/utils/dumper.cc -- utility to create core file.

EZ> Does this mean that the segfaulting application itself doesn't write
EZ> the core file?

no, "kernel", i.e. cygwin1.dll in case of cygwin, is doing the job. when
application triggers exception that is supposed to cause core dump,
cygwin1.dll calls external utility passing crashed program pid and
path to it. this utility scans crashed program address space and
writes needed portions of it to the core file. so crashed program
address space isn't changed while core is being dumped.

Egor.            mailto:deo AT logos-m DOT ru ICQ 5165414 FidoNet 2:5020/496.19