Re: [PATCH] trim memory not covered by WB MTRRs

[Jesse Barnes]

On Wednesday, June 27, 2007 10:02:35 Pim Zandbergen wrote:
> Jesse Barnes wrote:
> > It looks like end_pfn might be ~0UL now... can you print that out
> > in your configuration?
>
> Er, do you need the value of end_pfn ?
> Here's what I changed:
>
> if ((highest_addr >> PAGE_SHIFT) != end_pfn) {
>          printk(KERN_WARNING "***************\n");
>          printk(KERN_WARNING "**** WARNING: likely BIOS bug\n");
>          printk(KERN_WARNING "**** MTRRs don't cover all of "
>                 "memory, trimmed %lu pages\n", end_pfn -
>                 (highest_addr >> PAGE_SHIFT));
>          printk(KERN_WARNING "**** end_pfn before = %lu\n", end_pfn);
>          end_pfn = highest_addr >> PAGE_SHIFT;
>          printk(KERN_WARNING "**** end_pfn after = %lu\n", end_pfn);
>          printk(KERN_WARNING "***************\n");
> }
>
> Here's the result:
> ***************
> **** WARNING: likely BIOS bug
> **** MTRRs don't cover all of memory, trimmed 18446744073709486080
> pages **** end_pfn before = 2293760
> **** end_pfn after = 2359296
> ***************
>
> Hope that's what you needed.

Yeah, that's what I needed.  end_pfn looks ok, but I guess my test is a 
little too precise.  It should be if ((highest_addr >> PAGE_SHIFT) < 
end_pfn) rather than !=.  That should keep it from trying to extend 
your memory with bogus math.  I thought that the two values should 
always match, but I guess slightly different memory configurations 
might break that assumption.

Thanks,
Jesse
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