Re: Process memory map

[John Baldwin <jhb@FreeBSD.org>]

On 11/3/21 12:20 AM, Chris Packham via Gdb wrote:
> On Wed, Nov 3, 2021 at 1:33 PM Howard Chu <hyc@symas.com> wrote:
>>
>> Is the complete map of process address space saved in a core file? When debugging
>> with a core file, is there a gdb command to mmap the files that were mapped at the
>> time the core was taken, so that references to addresses in those regions will be
>> valid?
> 
> I recently had a similar need. I found `info proc all` (technically
> `info proc mappings`) contained the mapping info I needed. For a
> regular core file the shared libraries were automatically loaded (in
> my case I needed to `set auto-load safe-path` and `set sysroot` for my
> cross-build environment). The one slight problem I had was with a very
> specific core file where the crash was in ld.so in that specific case
> it wasn't automatically loaded and I had to muck around with `add
> symbol-file` and manually working out some offsets to get it loaded
> into the right place.
> 
> I'd be interested in hearing tips from anyone else.

Note that manually loading symbols is much easier in recent versions of
GDB.  You can find the base address that a given file is loaded at
via 'info proc mappings' and then just use
'add-symbol-file -o <base address> /path/to/library' to load all of the
symbols without having to calculate the address of individual sections.

-- 
John Baldwin