On 30/09/15 12:32, Mark Rutland wrote:

On Wed, Sep 30, 2015 at 11:45:15AM +0100, Julien Grall wrote:

quoted

Hi all,

Hi,

quoted

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.

Just to check, would this be expected to work with a 16K DomU (e.g.
[2])?

From a quick scan it looks like the relaxations provided by this series
should work so long as PAGE_SIZE % XEN_PAGE_SIZE == 0, assuming I
haven't missed something.

Correct, this series is able to cope with any PAGE_SIZE as long as it's
a multiple of the granularity used by Xen (i.e 4KB on ARM).

quoted

There is room for improvement, such as support of 64KB grant, modification
of PV protocol to support different page size... They will be explored in a
separate patch series later.

TODO list:
    - Convert xenfb to 64KB
    - Support for multiple page ring support
    - Support for 64KB in gnttdev
    - Support of non-indirect grant with 64KB frontend (patch sent [1])
    - It may be possible to move some common define between
    netback/netfront and blkfront/blkback in an header

Would any of these require more work to also handle 16K?

No. It should just boot on Xen as long as the CPU is support 16K
granularity.

Regards,

-- 
Julien Grall