CONFIG_X86_CMPXCHG on Intel 386 still needed?

Gilles Chanteperdrix gilles.chanteperdrix at laposte.net
Mon Oct 4 17:07:02 CEST 2004


Edelhard Becker wrote:
 > Hi,
 > 
 > we want to use RTAI on low-cost 386EX based boards. In 3.x, the
 > availability of CONFIG_X86_CMPXCHG in the kernels .config is checked
 > by RTAIs configure.  From the comments in arch/i386/kernel/emu.c i'd
 > expect that this check is not necessary when the kernel option
 > CONFIG_X86_EMU486 is set. With the attached patch to RTAIs (3.1)
 > configure at least it compiles fine. So is the check for "hardware-
 > cmpxchg()" still needed?

a "grep cmpxchg" run in vesuvio sources, shows that it is used in the
implementation of the following components :
fifos
semaphores
shared memory
netrpc

and in the following headers :
rtai_posix.h
rtai_scb.h

So, if you want to disable the check in configure.in, you should provide
a cli/sti based implementation of the atomic_cmpxchg macro.

Regards.

-- 


					    Gilles Chanteperdrix.




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