Re: [Xen-devel] PVH Dom0 Intel IOMMU issues

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 18.04.17 at 09:34, <roger.pau@xxxxxxxxxx> wrote:
> (XEN) Before DMA_GCMD_TE
> (
> 
> The hang seems to happen when writing DMA_GCMD_TE to the global command
> register, which enables the DMA remapping. After that the box is completely
> unresponsive, not even the watchdog is working.

How sure are you that this is pre-Haswell specific vs e.g. chipset or
firmware (think of RMRRs [or their lack] for the latter) dependent?
Iirc Elena's command line specifiable RMRR patch series was
motivated by similar behavior she had observed on some system.

Another odd aspect is - why would IOMMU enabling cause the hang
only when intending to use a PVH Dom0? The IOMMU is being
enabled in either case, which again might point at differences in use
of memory.

Jan


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