Re: [Xen-devel] pvops: AHCI problems with SB600

[Jeremy Fitzhardinge <jeremy@xxxxxxxx>]

On 09/23/09 13:09, Jeremy Fitzhardinge wrote:
>               if (!no_iommu &&
>                   max_pfn > MAX_DMA32_PFN &&
>                   !printed_gart_size_msg) {
>                       printk(KERN_ERR "you are using iommu with agp, but GART 
> size is less than 64M\n");
>                       printk(KERN_ERR "please increase GART size in your BIOS 
> setup\n");
>                       printk(KERN_ERR "if BIOS doesn't have that option, 
> contact your HW vendor!\n");
>                       printed_gart_size_msg = 1;
>               }
>   

Oh, that's the wrong error message, but the other one has similar
predicates.  Hm, but it also skips the test if (swiotlb && !valid_agp)...

> I guess the "!no_iommu" clause is triggering because we have swiotlb
> set, but I wonder if that's specifically testing for the presence of a
> GART IOMMU?
>
> How does ioremap_nocache fit into this?  Is the mapping failing in some
> way and causing this code to fail?  Or am I misunderstanding?
>
>   
>> This is exhibited only when dom0 has more than 4GB, so if you do 
>> dom_mem=max:4GB
>> the machine boots succesfully.
>>   
>>     
> The test above also tests "max_pfn > MAX_DMA32_PFN" which limiting
> memory would avoid.
>   

    J

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