Re: [Xen-merge] Odd diff in mpparse.c

[Arun Sharma <arun.sharma@xxxxxxxxx>]

Martin J. Bligh wrote:
> Maybe it's just too late to be piddling around with this still .. but ...
>
> I don't understand this diff section:
>
>
> @@ -690,7 +697,7 @@ void __init get_smp_config (void)
>                  * Read the physical hardware table.  Anything here will
>                  * override the defaults.
>                  */
> -               if (!smp_read_mpc((void *)mpf->mpf_physptr)) {
> +               if (!smp_read_mpc(isa_bus_to_virt(mpf->mpf_physptr))) {
>                         smp_found_config = 0;
>                         printk(KERN_ERR "BIOS bug, MP table errors detected!...\
> n");
>                         printk(KERN_ERR "... disabling SMP support. (tell your h
> w vendor)\n");
>
>
> That's going from the standard to the xen base. Obvious thing is 
> to just abstract out isa_bus_to_virt, etc. But ...How the hell was
> that working in teh first plae, seems like we're passing a phys ptr
> into something that's expecting a virtual address ???? The xen version
> looks fine, it's the original that worries me.
The original code takes advantage of a direct mapping (phys = virtual) 
that goes away in later stages of booting.
        -Arun

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