About the workaround for the 484863 L220 erratum

[Catalin Marinas]

On 4 December 2012 13:29, Will Deacon <will.deacon at arm.com> wrote:
> On Tue, Dec 04, 2012 at 12:57:57PM +0000, Asano, Yasushi wrote:
>> I am looking for a workaround for the 484863 L220 erratum.
>> "484863: The Cache Sync operation does not guarantee that the Eviction Buffer is empty"
>>
>> Then I found a patch as below.
>> http://www.linux-arm.org/git?p=linux-2.6-stable.git;a=commitdiff;h=61f0ab1658f41f34c1910848063c565095a47864
...
>> Could you please tell me if you know the reason why it does not get into the mainline.
>
> Probably because, looking at the patch in question, it uses a swp
> instruction in the kernel which could be fatal if we have swp emulation
> enabled (we only emulate for user mode).

Another reason I remember is that swp on that register caused hardware
deadlocks on some platforms. So the workaround is highly dependent on
the L2 wiring.

-- 
Catalin