Re: 64bit startup

[Samuel Thibault]

Sergey Bugaev, le ven. 26 mai 2023 17:31:40 +0300, a ecrit:
> On Fri, May 26, 2023 at 2:15 PM Samuel Thibault <samuel.thibault@gnu.org> 
> wrote:
> > It does load, but stays stuck when starting ext2fs:
> >
> >    start ext2fs:
> 
> Yes, I can reproduce this with your build of ext2fs.static
> 
> Unfortunately there are no symbols (maybe you could teach me how to
> fetch and load separate debuginfo into gdb?), but it's crashing on:
> 
>    0x000000000055cd00: push   %rbp
>    0x000000000055cd01: mov    %esi,%eax
>    0x000000000055cd03: mov    %rdx,%rsi
>    0x000000000055cd06: mov    %rsp,%rbp
>    0x000000000055cd09: push   %r13
>    0x000000000055cd0b: push   %r12
>    0x000000000055cd0d: push   %rbx
>    0x000000000055cd0e: sub    $0x1048,%rsp
> => 0x000000000055cd15: mov    %fs:0x28,%rdx
> 
> (gdb) p $fs_base
> $2 = 0
> 
> %fs:0x28 is tcb->stack_guard. The function is thread_set_state, I
> believe -- it's trying to set this very fs_base to the
> __init1_tcbhead. Clearly it gets built with the stack guard in
> your/Debian build, but not in mine or Flavio's.

--enable-stack-protector=strong has been a default in debian for a long
time indeed. I guess we just need to add more of 

mach/Makefile:CFLAGS-mach_init.o = $(no-stack-protector)

for now I'll disable the protector by hand to get something working.

> > BTW, it seems the control-alt-d kdb shortcut is not working?
> 
> I didn't enable kdb in my gnumach build. I never learned how to use it.

You really should, it's terribly useful to inspect tasks etc.

show all tasks
trace/t $task1.4

etc.

Samuel