Re: [Xen-devel] [RFC PATCH 01/35] Add XEN config options and disable unsupported config options.

Christian Limpach
2006-05-10T15:48:29Z

On Wed, May 10, 2006 at 04:36:58PM +0100, Alan Cox wrote:
> On Maw, 2006-05-09 at 00:00 -0700, Chris Wright wrote:
> > plain text document atodiad (config-xen)
> > The XEN config option is selected from the i386 subarch menu by
> > choosing the X86_XEN "Xen-compatible" subarch.
>
> You need this as well. At least if I read the logic right with regards
> to Xen and traps it is safe to do the following (although probably not
> safe to run Xen on such a physical system anyway)

Yes. In our tree, we have a config option which completely removes
all the hardware idt table code (X86_NO_IDT) and stores the trap
table as a table suitable to pass directly to the hypervisor.

That's not so useful if you want to build a kernel which can run
both on a hypervisor and on native. I guess you would need to
disable the X86_F00F_BUG code at runtime in such a kernel.

For the non-runtime case, I wonder if it's preferable to disable
X86_F00F_BUG like you suggest or if it would be better to disable
the cpu types listed?

christian

>
> Signed-off-by: Alan Cox <alan@redhat.com>
>
> --- arch/i386/Kconfig.cpu~ 2006-05-10 15:51:44.956941304 +0100
> +++ arch/i386/Kconfig.cpu 2006-05-10 15:51:44.956941304 +0100
> @@ -251,7 +251,7 @@
>
> config X86_F00F_BUG
> bool
> - depends on M586MMX || M586TSC || M586 || M486 || M386
> + depends on ( M586MMX || M586TSC || M586 || M486 || M386 ) && !XEN
> default y
>
> config X86_WP_WORKS_OK
>
>