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Re: i386 Linux signal trampoline support for gdb 4.18


On Thu, Jul 15, 1999 at 10:07:32PM +0200, Ian Lance Taylor wrote:
>    The code needs to be changed to handle syscall 173 too, otherwie it'll
>    lose with RT signals.
> 
> I unfortunately don't use glibc 2.1, so I can't test either of these
> options.

rt signals are not glibc 2.1 specific, you can use them with glibc 2.0
too if you include the kernel include files directly (it is a bit tricky
though because glibc and kernel ABI is different and you have to be careful
that you get the right structures in all cases)

To handle the RT signal in pre glibc-2.2 should be simple, just make it 
recognize:

movl $173,%eax ; int $0x80
0xb8 0xad 00 00 00 0xcd 0x80 

as trampoline too (actually only the system call number is different)


> As far as I can tell, my patch is still appropriate, so that gdb will
> work correctly on systems using older glibc versions.  It will need to
> be enhanced for later glibc versions, but it will also work correctly
> as is; it will simply fail to recognize signal trampolines when using
> glibc 2.1, which is exactly what happens without my patch.

Of course, I just wanted to point out the libc problem. 

-Andi

-- 
This is like TV. I don't like TV.

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