Re: [Qemu-devel] [PATCH QEMU-XEN v4 3/9] xen: Switch to libxengnttab interface for compat shims.

[Ian Campbell <ian.campbell@citrix.com>]

On Fri, 2015-10-23 at 12:06 +0100, Stefano Stabellini wrote:
> On Wed, 21 Oct 2015, Ian Campbell wrote:
> > In Xen 4.7 we are refactoring parts libxenctrl into a number of
> > separate libraries which will provide backward and forward API and ABI
> > compatiblity.
> > 
> > One such library will be libxengnttab which provides access to grant
> > tables.
> > 
> > In preparation for this switch the compatibility layer in xen_common.h
> > (which support building with older versions of Xen) to use what will
> > be the new library API. This means that the gnttab shim will disappear
> > for versions of Xen which include libxengnttab.
> > 
> > To simplify things for the <= 4.0.0 support we wrap the int fd in a
> > malloc(sizeof int) such that the handle is always a pointer. This
> > leads to less typedef headaches and the need for
> > XC_HANDLER_INITIAL_VALUE etc for these interfaces.
> > 
> > Build tested with 4.0 and 4.5.
> > 
> > Note that this patch does not add any support for actually using
> > libxengnttab, it just adjusts the existing shims.
> > 
> > Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
> 
> The patch looks OK but doesn't apply cleanly to master, please rebase.
> After fixing it up, it fails my 4.0 build test (I probably made a
> mistake).

There was a new xc_gnttab_munmap which needed converting.

BTW, contrary to what every single commit message here says I'm actually
build testing on: xen with my other patches from this mega series, 4.6,
4.1, 4.0, 4.5, 4.4, 4.3, 4.2 and on my dev xen with pvbuilder forced to on.
I'm just going to drop all these "Build tested.." from the commit messages.

(the strange version ordering is so I test the different API classes first
and fail early on problems and then fill in the gaps).

Ian.