Re: Problems with alpha/pci + radeon/ttm

[Matt Turner <mattst88@gmail.com>]

On Sun, Jun 27, 2010 at 12:20 AM, FUJITA Tomonori
<fujita.tomonori@lab.ntt.co.jp> wrote:
> On Thu, 24 Jun 2010 10:53:52 -0400
> Matt Turner <mattst88@gmail.com> wrote:
>
>> > Seems that the IOMMU can't find 128 pages. It's likely due to:
>> >
>> > - out of the IOMMU space (possibly someone doesn't free the IOMMU
>> >  space).
>> >
>> > or
>> >
>> > - the mapping parameters (such as align) aren't appropriate so the
>> >  IOMMU can't find space.
>> >
>> >
>> >> Is this the cause of the bug we're seeing in the report [1]?
>> >>
>> >> Anyone know what's going wrong here?
>> >
>> >
>> > I've attached a patch to print the debug info about the mapping
>> > parameters.
>> >
>> >
>> > diff --git a/arch/alpha/kernel/pci_iommu.c b/arch/alpha/kernel/pci_iommu.c
>> > index d1dbd9a..17cf0d8 100644
>> > --- a/arch/alpha/kernel/pci_iommu.c
>> > +++ b/arch/alpha/kernel/pci_iommu.c
>> > @@ -187,6 +187,10 @@ iommu_arena_alloc(struct device *dev, struct pci_iommu_arena *arena, long n,
>> >        /* Search for N empty ptes */
>> >        ptes = arena->ptes;
>> >        mask = max(align, arena->align_entry) - 1;
>> > +
>> > +       printk("%s: %p, %p, %d, %ld, %lx, %u\n", __func__, dev, arena, arena->size,
>> > +              n, mask, align);
>> > +
>> >        p = iommu_arena_find_pages(dev, arena, n, mask);
>> >        if (p < 0) {
>> >                spin_unlock_irqrestore(&arena->lock, flags);
>>
>> Using this patch, I log the attached output.
>
> Your system has 1GB iommu address space. I guess that it's enough for
> KSM?

I would definitely think so. The video card I'm using here is a 64MB
Radeon 9100 PCI, with a 128MB BAR.

> The parameters in the log looks good. But you got this log before you
> started X?

Yes, that's right.

I'll see if I can isolate where the first -ENOMEM is coming from.

Thanks Fujita for helping with this!

Matt