[patch] Fix linux-ia64 on SIGILL for deleted breakpoint

[Tristan Gingold]

On Jul 19, 2010, at 11:19 AM, Jan Kratochvil wrote:

> On Mon, 19 Jul 2010 11:04:26 +0200, Tristan Gingold wrote:
>> On Jul 19, 2010, at 10:58 AM, Jan Kratochvil wrote:
>>> in some cases ia64 can generate SIGILL instead of SIGTRAP.  Guessing it is
>>> a CPU bug instead of Linux kernel bug (but I may be wrong).
>>> 	https://bugzilla.redhat.com/show_bug.cgi?id=615538
>>> 	http://sources.redhat.com/cgi-bin/cvsweb.cgi/~checkout~/tests/ptrace-tests/tests/ia64-sigill.c?cvsroot=systemtap
>> 
>> This is not a bug but a feature: the immediate of break.b is ignored by the processor.
> 
> You are right, Intel IA64 manual says:
> 	For the b_unit_form, imm21 is ignored and the value zero is placed in
> 	the Interruption Immediate control register (IIM).

Yes, this is an amazing weirdness, which might be difficult to work-around before tukwila.