Re: [Xen-devel] [xen-unstable test] 24366: tolerable trouble: broken/fail/pass

[Ian Campbell <Ian.Campbell@xxxxxxxxxx>]

On Thu, 2014-01-16 at 14:29 +0000, Ian Campbell wrote:
> On Thu, 2014-01-16 at 14:22 +0000, Stefano Stabellini wrote:
> > LVM works for me, but I am not using udev at the moment.
> 
> I instrumented the guest f/s and blkfront and it seems like reads are
> returning buffers full of 0xc2c2c2c2, which is the pattern that Xen
> scrubs pages with in a debug build.
> 
> So either there is a cache coherency issue or perhaps something to do
> with the dom0 swiotlb doing direct i/o to guest pages and sending them
> to the wrong place.

Just to close this off -- the issue here turned out to be truncation of
dma addresses from 64-bits to 32-bits when LPAE is not enabled. Fixed by
my Linux patch "xen: swiotlb: handle sizeof(dma_addr_t) !=
sizeof(phys_addr_t)".

Ian.



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