CONFIG_X86_CMPXCHG on Intel 386 still needed?

Philippe Gerum rpm at
Mon Oct 4 17:14:03 CEST 2004

Hi Edelhard,

On Mon, 2004-10-04 at 16:48, 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?

AFAIK, the 486 emulation patch is not available in vanilla kernels; that
would be the only problem. What could be done however, is testing for
CONFIG_X86_EMU486 in, so that we don't bail out due to
missing cmpxchg() when set.

> Greetings,
> Edelhard


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