Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is notenough ram for it

From: Shuah Khan
Date: Fri Jan 04 2013 - 21:02:55 EST

On Fri, Jan 4, 2013 at 4:55 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Fri, Jan 4, 2013 at 3:21 PM, Shuah Khan <shuahkhan@xxxxxxxxx> wrote:
>> Please see attached dmesg for full log. I can do some testing on this
>> system with your patch if you would like.
> That would be great.
> Please try
> git://
> for-x86-boot
> or just this patch.
> Too bad, I can not access AMD systems with IOMMU support.
> Thanks a lot.

I tried your patch on my AMD system. I did change the patch to print
warning instead of panic() and it did trigger the condition for

[ 5.376654] AMD-Vi: Found IOMMU at 0000:00:00.2 cap 0x40
[ 5.376717]
[ 5.376799] pci 0000:00:00.2: irq 72 for MSI/MSI-X

It would have panic'ed here:

[ 5.388858] AMD-Vi: can not enable swiotlb for unhandled devices by
AMD iommu!

[ 5.388964] AMD-Vi: Lazy IO/TLB flushing enabled
[ 5.389324] LVT offset 0 assigned for vector 0x400

I applied your patch to 3.6.11 and changed the panic() to pr_info()
and also changed enough_mem_for_swiotlb() to always return false to
simulate not enough memory condition as this system does have enough

So at least on this AMD system, your patch will result in a panic.

-- Shuah
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