Re: [Xen-devel] [xen-unstable] Commit 2ca9fbd739b8a72b16dd790d0fff7b75f5488fb8 AMD IOMMU: allocate IRTE entries instead of using a static mapping, makes dom0 boot process stall several times.

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.07.13 at 22:50, Sander Eikelenboom <linux@xxxxxxxxxxxxxx> wrote:
> After commit 2ca9fbd739b8a72b16dd790d0fff7b75f5488fb8 AMD IOMMU: allocate 
> IRTE entries instead of using a static mapping, booting dom0 stalls several 
> times.
> Sometimes this results in RCU stall warnings from the dom0 kernel, hitting 
> the "any" key, on normal or serial console, makes the boot continue for a 
> while but it stalls several times.
> (It also stalls on shutdown BTW)
> 
> I have bisected it to this commit running kernel 3.10.2 and Debian wheezy.
> 
> xl-dmesg and dmesg from a boot with stall are attached, snippet from dmesg 
> with RCU stall appended below.
> 
> Note that i do have to run with iommu='no-amd-iommu-perdev-intremap' due to 
> the 
> bios bug that probably will never get fixed.
> When i run without the 'no-amd-iommu-perdev-intremap' the iommu is disabled 
> and 
> stalls do not occur.

I can only hope that someone with access to a system exposing this
problem (you?) can debug it - I certainly have no system where this
issue could be seen, and I don't recall Suravee having noticed
anything like this in his testing of those patches.

Jan


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