Linux Virtualization - Sep 2014 - [Qemu-devel] [PATCH 1/2] virtio-gpu/2d: add hardware spec include file

On Sun, Sep 14, 2014 at 07:32:21AM -0700, Peter Maydell
wrote:
> On 14 September 2014 07:11, Michael S. Tsirkin <mst at redhat.com>
wrote:
> > On Sun, Sep 14, 2014 at 07:04:11AM -0700, Peter Maydell wrote:
> >> On 14 September 2014 06:46, Michael S. Tsirkin <mst at
redhat.com> wrote:
> >> > BUILD_BUG_ON in linux, QEMU_BUILD_BUG_ON in QEMU.
> >> > You have to stick it in a C file though, so it
> >> > won't be visible in this patch.
> >>
> >> Why do you think that? We have several header files which
> >> use QEMU_BUILD_BUG_ON and I don't see any reason why
> >> it would have to be invoked from a .c file.
> 
> > Because Gerd wants to share this with linux uapi, and
> > you can't use BUILD_BUG_ON in uapi headers on linux.
> 
> Who owns the "master" copy of the header and commits
> to making sure it builds on other things than Linux+gcc
> in that case?
> 
> -- PMM
For most of virtio neither linux nor QEMU are the master.
syncing them has been done manually in the past.
As we are copying other headers from Linux anyway,
I think it would be better for everyone if we make
the Linux headers the master for QEMU going forward.

-- 
MST

On 14 September 2014 08:09, Michael S. Tsirkin <mst at redhat.com>
wrote:
> On Sun, Sep 14, 2014 at 07:32:21AM -0700, Peter Maydell wrote:
>> Who owns the "master" copy of the header and commits
>> to making sure it builds on other things than Linux+gcc
>> in that case?
> For most of virtio neither linux nor QEMU are the master.
> syncing them has been done manually in the past.
> As we are copying other headers from Linux anyway,
> I think it would be better for everyone if we make
> the Linux headers the master for QEMU going forward.
That's problematic because our copies of the linux headers
are only (and can only) be included in our include path
on Linux hosts. I had this problem with the PSCI headers
for ARM (I can't say I really like the solution I came up
with there, so if we can do better that would be cool).

-- PMM

On Sun, Sep 14, 2014 at 09:11:45AM -0700, Peter Maydell
wrote:
> On 14 September 2014 08:09, Michael S. Tsirkin <mst at redhat.com>
wrote:
> > On Sun, Sep 14, 2014 at 07:32:21AM -0700, Peter Maydell wrote:
> >> Who owns the "master" copy of the header and commits
> >> to making sure it builds on other things than Linux+gcc
> >> in that case?
> 
> > For most of virtio neither linux nor QEMU are the master.
> > syncing them has been done manually in the past.
> > As we are copying other headers from Linux anyway,
> > I think it would be better for everyone if we make
> > the Linux headers the master for QEMU going forward.
> 
> That's problematic because our copies of the linux headers
> are only (and can only) be included in our include path
> on Linux hosts. I had this problem with the PSCI headers
> for ARM (I can't say I really like the solution I came up
> with there, so if we can do better that would be cool).
> 
> -- PMM
Right. My idea was to add stuff that's used on all platforms
to some other directory (besides linux-headers).
I didn't try to implement this yet so I don't know whether
there are any issues with this.
Should be better than duplicating it manually.

-- 
MST