Re: [Qemu-devel] [PATCH] include: update Linux headers to 4.21/5.0

[Peter Maydell]

On Thu, 3 Jan 2019 at 18:19, Michael S. Tsirkin <address@hidden> wrote:
>
> On Thu, Jan 03, 2019 at 06:51:13PM +0100, Paolo Bonzini wrote:
> > Signed-off-by: Paolo Bonzini <address@hidden>
>
> Note that in the past we just updated what we needed.

Not if I noticed it -- our copies of the Linux headers
are supposed to always be synchronized entirely from
a commit of Linux upstream master. Ad-hoc cherry-picked
changes can easily be accidentally undone by a later sync
by somebody else. This is why we have an automatic
script to do header synchronization, so we don't have
to manually write and review header updates.

> I'd prefer the shell script part and the new vhost_types header which
> are actually reviewable to be split out to a separate patch.

I agree that shell script changes should be their own patch.
My view is that a header-update commit should be entirely
and nothing but the automatically generated results of
running scripts/update-linux-headers.sh, with a commit
message that says "Generated by running update-linux-headers.sh
on upstream kernel commit xxxx". Then (assuming you trust the
person who did that to do what they say in the commit message
they're doing) you don't need to actually review the changes
in detail.

Doing by-hand updates to the headers is quite a common
error; I'm not sure if we can automatically catch it
with checkpatch. ("Any change to include/standard-headers
or linux-headers/ must be a commit that touches only files
in those subdirectories and whose commit message is in
a standard format", perhaps.)

thanks
-- PMM