[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [RFC 00/23] arm64: Add support for 64KB page granularity in Xen guest
On Mon, 18 May 2015, Julien Grall wrote: > Hi David, > > On 15/05/15 16:45, 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? > > Even with the helpers, we are not protected from any change in the > frontend/backend that will impact 64K. It won't be possible to remove > all the XEN_PAGE_* usage (there is a lots of places where adding helpers > would not be possible) and we would still have to carefully review any > changes. We could at least introduce a few asserts, so that an ARM64 kernel build, that any x86 maintainers can easily and quickly do on their x86 machines, would spot these errors. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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