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Date: Fri, 11 Jan 2013 11:35:48 -0500
From: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
To: Yinghai Lu <yinghai@kernel.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>,
        Shuah Khan <shuahkhan@gmail.com>, Thomas Gleixner <tglx@linutronix.de>,
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        Jason Wessel <jason.wessel@windriver.com>,
        linux-kernel@vger.kernel.org, Joerg Roedel <joro@8bytes.org>
Subject: Re: [PATCH v7u1 26/31] x86: Don't enable swiotlb if there is not
 enough ram for it
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On Thu, Jan 10, 2013 at 03:07:10PM -0800, Yinghai Lu wrote:
> On Wed, Jan 9, 2013 at 1:15 PM, Yinghai Lu <yinghai@kernel.org> wrote:
> > On Wed, Jan 9, 2013 at 1:00 PM, Eric W. Biederman <ebiederm@xmission.com> wrote:
> >> Yinghai Lu <yinghai@kernel.org> 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.

I'm the frontline maintainer of swiotlb and related stuff so if you want to follow
the proper protocol you should wait until I give you my Ack.

I need to check this patch out and then also test-run them on IA64, AMD-VI, Calgary-X
GART and Intel VT-d to make a sanity test.

However, this particular patch can go outside the mega-patchset you have. So you
could post the mega-patchset to hpa without this being in it and just mention
that there is this extra one that Konrad is handling.