bug#24682: 26.0.50; Bootstrap failed

[Eli Zaretskii]

> From: Michael Albinus <michael.albinus@gmx.de>
> Cc: 24682@debbugs.gnu.org
> Date: Fri, 14 Oct 2016 16:40:18 +0200
> 
> gdb --args ./temacs --batch  --load loadup bootstrap
> GNU gdb (Ubuntu 7.12-0ubuntu1) 7.12
> 
> [...]
> 
> Loading /home/albinus/src/emacs/lisp/cus-start.el (source)...
> Loading /home/albinus/src/emacs/lisp/tooltip.el (source)...
> Finding pointers to doc strings...
> Finding pointers to doc strings...done
> Dumping under the name emacs
> 20599360 of 33554432 static heap bytes used
> 
> Program received signal SIGSEGV, Segmentation fault.
> __memcpy_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:130
> 130   ../sysdeps/x86_64/multiarch/memcpy-ssse3.S: No such file or directory.
> (gdb) bt
> #0  __memcpy_ssse3 () at ../sysdeps/x86_64/multiarch/memcpy-ssse3.S:130
> #1  0x0000555555707f8b in memcpy (__len=1465781148, __src=0x781464, 
>     __dest=0x7fff8fc1a464) at /usr/include/x86_64-linux-gnu/bits/string3.h:53
> #2  unexec (
>     new_name=0x555557049248 <bss_sbrk_buffer+19825800> 
> "/usr/local/src/emacs/src/emacs", 
>     old_name=0x555557049270 <bss_sbrk_buffer+19825840> 
> "/usr/local/src/emacs/src/temacs") at unexelf.c:406
> #3  0x000055555565bea7 in Fdump_emacs (filename=93825020178884, 
>     symfile=<optimized out>) at emacs.c:2157

Isn't the value of __len (about 1.4GB) too large?  unexelf.c:406 is
this:

  /* Copy over what we have in memory now for the bss area. */
  memcpy (new_base + new_data2_offset, (caddr_t) old_bss_addr,
          bss_size_growth);

So bss_size_growth is about 1.4GB, which sounds incredibly large.

the value is computed on line 334, can you tell the values of the two
variables that get subtracted there?