Re: [Xen-devel] [PATCH v2 0/2] Remove PAGE_SIZE from public headers

[Stefano Stabellini <sstabellini@xxxxxxxxxx>]

On Thu, 20 Oct 2016, Juergen Gross wrote:
> On 19/10/16 21:21, stefano@xxxxxxxxxxx wrote:
> > Reference to PAGE_SIZE slipped in to two public header files. QEMU build on
> > ARM64 is broken by this. PAGE_SIZE should not be used because it could
> > be undefined or it could be defined differently on different operating
> > systems.
> > 
> > Stefano Stabellini (2):
> >       usbif.h: replace PAGE_SIZE with USBIF_RING_SIZE
> >       vscsiif.h: replace PAGE_SIZE with VSCSIIF_PAGE_SIZE
> > 
> >  xen/include/public/io/usbif.h   | 5 +++--
> >  xen/include/public/io/vscsiif.h | 3 ++-
> >  2 files changed, 5 insertions(+), 3 deletions(-)
> > 
> 
> In principle I'm okay with these changes. But wouldn't it be
> better to add
> 
> #define XEN_RING_PAGE_SIZE 4096
> 
> to xen/include/public/io/ring.h instead of having each interface
> file its own definition?

I would prefer to avoid having to spell out the page size for all the io
interfaces, because the same interfaces should work fine with other page
granularities, if the grant table hypercalls supported them.

However in reality frontend and backend would have to agree on the page
granularity to use beforehand. Some sort of consensus protocol is
required. When that protocol is introduced, we could get rid of
#define XEN_RING_PAGE_SIZE 4096.

What do people think about this?

_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel