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

["Martin J. Bligh" <mbligh@xxxxxxxxxx>]

--On Friday, August 05, 2005 10:54:34 -0700 Arun Sharma <arun.sharma@xxxxxxxxx> 
wrote:

> 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.

Are we really still that early in the process? Maybe we are ... I know
we used to direct map the first 8MB ... I had to move the NUMA-Q tables
down for that to get it to boot, so I guess that makes sense. Pah, is
going to make the merging a mess. oh well ;-(

Thanks,

M.


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