re: toolchain/53918: X crashes on pinebook and stack unwinding broken

[matthew green <mrg%eterna.com.au@localhost>]

> Since my last update X does not start any more and the X process hangs 
> apparently trying to log a backtrace:
> 
> [Switching to LWP 1 of process 437]
> 0x0000fffffb816e00 in memset () from /usr/lib/libc.so.12
> (gdb) bt
> #0  0x0000fffffb816e00 in memset () from /usr/lib/libc.so.12
> #1  0x0000fffffb6d5218 in ?? () from /lib/libgcc_s.so.1
> #2  0x0000fffffb6d68b8 in _Unwind_Backtrace () from /lib/libgcc_s.so.1
> #3  0x0000fffffbe710b0 in backtrace (arr=<optimized out>, len=<optimized out>)
>     at /work/src/lib/libexecinfo/unwind.c:67
> #4  0x0000000200271d70 in xorg_backtrace ()
> #5  0x000000020026dc6c in ?? ()
> #6  0x0000fffffb79d750 in _opendir (name=<optimized out>)
>     at /work/src/lib/libc/gen/opendir.c:72
> Backtrace stopped: previous frame identical to this frame (corrupt stack?)
> 
> This failure to unwind is why this is in the toolchain category - real fixes
> for the X issue would be nice too ;-)

looks like a bug for libexecinfo() on arm64?  at least you
seem to have something beyond signals.  on amd64 nothing
from the actually faulting code is shown, just the signal
handler and below.


.mrg.