On Fri, Oct 11, 2019 at 11:31:30AM +0100, Suzuki K Poulose wrote:
> Hi Greg,
>
> On 11/10/2019 05:55, Greg KH wrote:
> > On Thu, Oct 10, 2019 at 02:19:43PM +0100, Suzuki K Poulose wrote:
> > > A signed feature value is truncated to turn to an unsigned value
> > > causing bad state in the system wide infrastructure. This affects
> > > the discovery of FP/ASIMD support on arm64. Fix this by making sure
> > > we cast it properly.
> > >
> > > This was inadvertently fixed upstream in v4.6 onwards with the following :
> > > commit 28c5dcb22f90113dea ("arm64: Rename cpuid_feature field extract routines")
> >
> > What prevents us from just taking that commit instead? You did not
> > document that here at all, which I thought I asked for.
>
> Sorry, I missed that part. So, that change introduces helpers to
> extract feature fields based on the sign. And it also depends on
>
> commit ff96f7bc7bf6 ("arm64: capabilities: Handle sign of the feature bit")
>
> which introduces "sign" bit for the "capability" list and modifies
> the generic capability->matches() helpers to use the hint to switch to the
> appropriate helpers.
That's ok, does that cause any problems? We always want the original
patch instead of a one-off patch as that way we do not diverge.
> I could backport parts of the commit 28c5dcb22f90 dropping the bits
> that affect the changes mentioned above.
Please do, that is always prefered as well, but do the first thing above
if at all possible.
> >
> > Also, you only need 12 digits for a sha1, 28c5dcb22f90 ("arm64: Rename
> > cpuid_feature field extract routines") would be just fine :)
>
> Yea, I understand. Its simply a pain to count the numbers, so I make sure
> to pickup something that looks larger than the 12 ;-). I will try to stick
> to that :-)
git show -s --abbrev-commit --abbrev=12 --pretty=format:"%h (\"%s\")%n"
will give you the correct format. I suggest making it a git alias :)
Or, use:
[core]
abbrev = 12
in your .gitconfig file.
thanks,
greg k-h
