On Wed, 2008-08-06 at 13:43 +1000, Jason White wrote:
> On Wed, Aug 06, 2008 at 12:57:21PM +1000, Russell Stuart wrote:
> > I tried conspy on linux-2.6-2.6.25 (the current kernel for
> > Lenny) and it worked. Trying it on 2.6.26 is going to take
> > some time. In the mean time could you post an strace of a
> > run of conspy showing the problem please.
>
> It's attached. I hope this helps.
This needs to be written down somewhere. I am not sure this is the
right place, but it is the only place I can think of.
I suspect this was a compiler bug in the compilers used by Debian's
build machines. Disassembling the conspy-1.4 binary in the Debian
archives, for these lines of code:
tty_result = ioctl(tty_handle, KDGKBMODE, &keyboard_mode);
if (tty_result == -1)
;
else if (keyboard_mode != K_XLATE && keyboard_mode != K_UNICODE)
this assembler is generated:
402009: 48 8d 94 24 20 87 00 lea 0x8720(%rsp),%rdx
402010: 00
402011: 31 c0 xor %eax,%eax
402013: be 44 4b 00 00 mov $0x4b44,%esi
402018: e8 f3 f3 ff ff callq 401410 <[EMAIL PROTECTED]>
40201d: 83 f8 ff cmp $0xffffffffffffffff,%eax
402020: 89 c3 mov %eax,%ebx
402022: 44 89 64 24 28 mov %r12d,0x28(%rsp)
402027: 0f 84 be 03 00 00 je 4023eb <[EMAIL PROTECTED]>
40202d: 48 8b 84 24 20 87 00 mov 0x8720(%rsp),%rax
402034: 00
402035: 48 83 f8 01 cmp $0x1,%rax
402039: 0f 95 c2 setne %dl
40203c: 48 83 f8 03 cmp $0x3,%rax
402040: 0f 95 c0 setne %al
402043: 84 d0 test %dl,%al
Note that at address 402039, %dl is set conditionally. Also notice that
neither %dl, nor any alias was initialised prior. It could of been the
value set at address 402009, but more likely it was whatever rubbish the
OS call at 402018 left in it. This would of course be OS version
dependant, which is what we see. (The program worked with 2.6.25, but
not 2.6.26).
The lenny compiler I am using isn't broken in the same way, so it always
produces a conspy binary that works. I am hoping the Debian builders
have been updated, and so just an upload of identical code will fix the
problem by forcing a recompile. Not that the version I am uploading is
identical, but I haven't made any changes to fix this particular problem
either.
The upload will happen with 24 hours.
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