Re: [Xen-devel] [RFC 00/23] arm64: Add support for 64KB page granularity in Xen guest

From: Boris Ostrovsky
Date: Fri May 15 2015 - 11:54:35 EST


On 05/15/2015 11:45 AM, David Vrabel wrote:
On 14/05/15 18:00, Julien Grall wrote:
Hi all,

ARM64 Linux is supporting both 4KB and 64KB page granularity. Although, Xen
hypercall interface and PV protocol are always based on 4KB page granularity.

Any attempt to boot a Linux guest with 64KB pages enabled will result to a
guest crash.

This series is a first attempt to allow those Linux running with the current
hypercall interface and PV protocol.

This solution has been chosen because we want to run Linux 64KB in released
Xen ARM version or/and platform using an old version of Linux DOM0.
The key problem I see with this approach is the confusion between guest
page size and Xen page size. This is going to be particularly
problematic since the majority of development/usage will remain on x86
where PAGE_SIZE == XEN_PAGE_SIZE.

I think it would be nice to keep XEN_PAGE_SIZE etc out of front and
backend drivers. Perhaps with a suitable set of helper functions?

I am thinking exactly the same thing as I am going over these patches.

-boris
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