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SubjectRe: [PATCH 01/17] kbuild: Disable -Waddress-of-packed-member for gcc 9
On Fri, Mar 22, 2019 at 02:58:51PM +0100, Arnd Bergmann wrote:
> On Thu, Mar 21, 2019 at 11:00 PM Andi Kleen <andi@firstfloor.org> wrote:
> >
> > From: Andi Kleen <ak@linux.intel.com>
> >
> > This warning is very noisy in a default build with gcc 9.
> > Move it into W=2 only.
> >
> > Cc: arnd@arndb.de
> > Cc: Masahiro Yamada <yamada.masahiro@socionext.com>
> > Signed-off-by: Andi Kleen <ak@linux.intel.com>
>
> I think W=2 is too aggressive. On many architectures, this finds
> real bugs and the false positives tend to be trivial to fix
> (by removing the bogus __packed annotation), which improves
> the generated code in the process.

It might waste more memory or make the data structure incompatible
with something external.

>
> Moving it to W=1 for the moment is probably fine, but ideally
> I think we should fix the kernel to behave according to the
> C standard.

Okay, so is there anybody working on this?

AFAIK it's not an issue on x86 at all.

-Andi

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