lkml.org 
[lkml]   [2022]   [Nov]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v4 1/1] virt: acrn: Mark the uuid field as unused
On Wed, Nov 16, 2022 at 06:04:37PM +0200, Andy Shevchenko wrote:
> On Wed, Nov 16, 2022 at 04:20:08PM +0100, Greg Kroah-Hartman wrote:
> > On Wed, Nov 16, 2022 at 03:29:31PM +0200, Andy Shevchenko wrote:
> > > On Wed, Nov 16, 2022 at 12:42:16PM +0100, Greg Kroah-Hartman wrote:
> > > > On Wed, Nov 16, 2022 at 11:22:54AM +0200, Andy Shevchenko wrote:
>
> ...
>
> > > > > - * @uuid: UUID of the VM. Pass to hypervisor directly.
> > > > > + * @uuid: Reserved (used to be UUID of the VM)
> > > >
> > > > If it's reserved, then don't you need to check for 0?
> > >
> > > Reserved in a way that it may content something we just don't care about.
> >
> > "reserved" in the kernel ioctls mean "must be 0 and we will test for it,
> > otherwise this is an empty/useless field that can never be touched again
> > in the future.
> >
> > Please spell it out in detail as to if you can ever use this later on,
> > and what the kernel will do (if anything) if it is set.
> >
> > And if "the kernel ignores it" then that means these bytes are now
> > "empty space never to be used again", right?
>
> Right, I will fix this in v5.
>
> ...
>
> > > > > + __u8 uuid[16];
> > > >
> > > > You just changed the type here, so what is that going to break in
> > > > userspace that depended on this being of a structure type and now it's
> > > > an array?
> > >
> > > It's the same. The previous was hidden behind additional type level.
> >
> > Same size, yes. Same C structure definition, no.
>
> It doesn't matter, see below.
>
> > > > And no other kernel changes needed? Shouldn't you warn if this field is
> > > > set?
> > >
> > > No, as pointed out in the commit message kernel never ever used this.
> >
> > That does not mean that userspace tools never did, right? You are
> > changing the structure definition, what tool just broke?
>
> The only tool has been amended like a year ago, so the answer is none.
> The commit message has links to the commits in question that made that
> amendment.
>
> Maybe I should remove Fixes tags? In such case we will very much know
> that no old tools will be run on the new kernel.

Please remove "fixes" as this doesn't "fix" anything.

thanks,

greg k-h

\
 
 \ /
  Last update: 2022-11-16 17:16    [W:0.053 / U:0.424 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site