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

From: Yinghai Lu
Date: Thu Jan 10 2013 - 18:07:00 EST


On Wed, Jan 9, 2013 at 1:15 PM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> On Wed, Jan 9, 2013 at 1:00 PM, Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote:
>> Yinghai Lu <yinghai@xxxxxxxxxx> writes:
>>
>>> please check updated attached. It should address all your request.
>>
>> There is one significant bug that I can see.
>>
>> swiotlb_print_info tests no_iotlb_memory but no_iotlb_memory is set
>> after swiotlb_init_with_tlb returns.
>
> there is another swiotlb_print_info calling from
> pci_swiotlb_late_init
>
> void __init pci_swiotlb_late_init(void)
> {
> /* An IOMMU turned us off. */
> if (!swiotlb)
> swiotlb_free();
> else {
> printk(KERN_INFO "PCI-DMA: "
> "Using software bounce buffering for IO (SWIOTLB)\n");
> swiotlb_print_info();
> }
> }
>
> so we need that checking when swiotlb == 1, but actually we can not
> allocate that before.

Eric, so the code is right to put checking in swiotlb_print_info ?

I'd like to post the whole patchset again and ask HPA to put them in tip/next
to catch -v3.9 merging window.

Thanks

Yinghai
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