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From: David Vrabel <david.vrabel@citrix.com>
To: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>
Cc: xen-devel@lists.xenproject.org,
	Vladimir Murzin <murzin.v@gmail.com>,
	Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH] xen: workaround for 64-bit size/alignment bitops
Date: Mon, 28 Apr 2014 10:10:08 +0100	[thread overview]
Message-ID: <535E1AF0.3090402@citrix.com> (raw)
In-Reply-To: <CAAHg+HhqaQszAUD5PVr78ym1EKvcmtLh+8-ZJjJAyOzfeeH0nw@mail.gmail.com>

On 28/04/14 09:47, Pranavkumar Sawargaonkar wrote:
> On 27 April 2014 14:39, Vladimir Murzin <murzin.v@gmail.com> wrote:
>> Xen assumes that bit operations are able to operate on 32-bit size and
>> alignment. For arm64 bitops are based on atomic exclusive load/store
>> instructions to guarantee that changes are made atomically. However, these
>> instructions require that address to be aligned to the data size. Because, by
>> default, bitops operates on 64-bit size it implies that address should be
>> aligned appropriately. All these lead to breakage of Xen assumption for bitops
>> properties.
>>
>> As a workaround address is aligned forcefully along with adjustment for bit
>> position.
>>
[...]
> 
> I have tried this patch on XGENE and works fine, I have managed to get
> dom0 and domU working with it.
> 
> Tested-by: Pranavkumar Sawargaonkar <pranavkumar@linaro.org>

Thanks.  Are there arm64 platforms that support Xen currently available
in 3.15?  Or can this wait until 3.16?

David

  reply	other threads:[~2014-04-28  9:10 UTC|newest]

Thread overview: 7+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2014-04-27  9:09 [PATCH] xen: workaround for 64-bit size/alignment bitops Vladimir Murzin
2014-04-28  8:47 ` Pranavkumar Sawargaonkar
2014-04-28  9:10   ` David Vrabel [this message]
2014-04-28  9:13     ` Ian Campbell
2014-04-28  9:13 ` Ian Campbell
2014-04-28 10:13   ` David Vrabel
2014-04-28 10:19     ` Ian Campbell

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