Re: Better debugging support in Mach

[Ludovic Courtès]

Hey!

Thomas Schwinge <thomas@schwinge.name> skribis:

> On Mon, 26 Mar 2012 21:51:18 +0200, ludo@gnu.org (Ludovic 
> =?iso-8859-1?Q?Court=E8s?=) wrote:

[...]

>> Yes, but ‘-fomit-frame-pointer’ is enabled “at levels `-O', `-O2',
>> `-O3', `-Os'” (info "(gcc) Optimize Options").
>> 
>> Anyway, building with “-O1 -fno-omit-frame-pointer” yields slightly
>> better, yet imperfect traces:
>> 
>>   db> show task
>>       TASK        THREADS
>>     5 (e0823c60): 4 threads:
>>                 0 (e083e548) R   F
>>                 1 (e083e2a8)  W   (0xc014c4b0) 0
>>                 2 (e084ce80) R    (0xc014c4b0)
>>                 3 (e084cbe0)  W   (0xc014c620) 0
>>   db> trace/tu
>>   0xc011eae9(c027c819,e0823c60,17,e083e548,e0847ef8)
>>   0xc014ee59(e0820dc0,17,e0847ef8,128bc70,a)
>>   0xc01529dc(1,17,e0847ef8,e0824d20,ea0359c8)
>>   0xc0106d40(128fdbc,2000,a,800,0)
>>   >>>>> user space <<<<<
>>   0x103ac3d(1,0,0,0,3a)
>>   0x103af69(804ccf8,80494ec,7530,0,0)
>>   0x804a2a3(1,128fed4,128fedc,f3d4,128fed4)
>>   Bad frame pointer: 0x1
>> 
>> and:
>> 
>>   $ addr2line -pfa -e result/hurd/auth 0x103ac3d 0x103af69 0x804a2a3
>>   0x0103ac3d: ??
>>   ??:0
>>   0x0103af69: ??
>>   ??:0
>>   0x0804a2a3: main at 
>> /tmp/nix-build-3bm2lp9lkj6bczd61p9qj1ramlpxy7wh-hurd-0-i586-pc-gnu.drv-0/hurd-20120326/auth/auth.c:523
>> 
>> The strange thing is that the top-most part is correct.
>
> I would bet this is ld.so/libc.so/etc.

Oops, indeed.

With a statically-linked auth, the situation is much better:

  $ addr2line -pfai -e result/hurd/auth 0x804cea5 0x804d1a0 0x8049a47 
0x8059ffa0 0xeb810811
  0x0804cea5: thread_function at 
/tmp/nix-build-j0kklj5b651rar28sqrglqd6x29l7sxx-hurd-0-i586-pc-gnu.drv-0/hurd-20120326/libports/manage-multithread.c:140
  0x0804d1a0: ports_manage_port_operations_multithread at 
/tmp/nix-build-j0kklj5b651rar28sqrglqd6x29l7sxx-hurd-0-i586-pc-gnu.drv-0/hurd-20120326/libports/manage-multithread.c:170
  0x08049a47: main at 
/tmp/nix-build-j0kklj5b651rar28sqrglqd6x29l7sxx-hurd-0-i586-pc-gnu.drv-0/hurd-20120326/auth/auth.c:523

Thanks!

Ludo’.