ARM64: Disabling warnings about deprecated armv8 instructions

Måns Rullgård mans at
Mon Jan 30 08:38:15 PST 2017

Ard Biesheuvel <ard.biesheuvel at> writes:

> On 30 January 2017 at 14:13, Russell King - ARM Linux
> <linux at> wrote:
>> On Sun, Jan 22, 2017 at 01:01:53PM +0000, Ard Biesheuvel wrote:
>>> Emulating unaligned access in the ARM kernel was a mistake: it even
>>> emulates unaligned accesses for instructions like ldm and ldrd, which
>>> require word alignment at the hardware level even in the latest v8
>>> version of the architecture. In contrast, the v8 deprecation warnings
>>> are about enforcing compliance.
>> Ard, you're totally wrong on the unaligned access thing.  Unaligned
>> accesses are a fundamental requirement of the kernel's networking
>> stack.  If you don't have support for unaligned accesses, then you
>> don't have network support - it's as simple as that.
>> So, in order for ARMv5 and earlier to have network support, there
>> was no option to add support for emulating those accesses.
> I wasn't aware of that.

Not even David Miller is "aware" of that.  Then again, we're living in a
world of "alternative facts" now.

Måns Rullgård

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