From: Keir Fraser <keir.xen@gmail.com>
To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xensource.com, tim@xen.org,
Ian Campbell <Ian.Campbell@citrix.com>
Subject: Re: [PATCH v3 3/3] xen: introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf
Date: Thu, 08 Aug 2013 15:47:05 +0100 [thread overview]
Message-ID: <CE296DF9.30566%keir.xen@gmail.com> (raw)
In-Reply-To: <alpine.DEB.2.02.1308081513470.4893@kaball.uk.xensource.com>
On 08/08/2013 15:16, "Stefano Stabellini" <stefano.stabellini@eu.citrix.com>
wrote:
>> This confused me too, this talk of contiguity and being below 4GB. Doesn't
>> this new hypercall behave *exactly* like XENMEM_exchange, except for the
>> additional pinning of the MFNs? If so, just say that in the patch header and
>> code comments. The fact *you* currently use it to get memory below 4GB is an
>> application detail.
>
> Yeah, you have a good point there. Trying to make the comment clearer I
> actually confused it. I'll fix it.
>
>
>> I wonder whether XENMEM_exchange is much use at all in the presence of
>> paging, without the additional semantics of pinning? Perhaps XENMEM_exchange
>> could be suitably adjusted to have the pinning semantics in this case?
>
> It's not just about pinning, we also need to get the mfn back even if
> the guest is autotranslate, that XENMEM_exchange doesn't do.
Ok, fine by me.
-- Keir
next prev parent reply other threads:[~2013-08-08 14:47 UTC|newest]
Thread overview: 30+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-08-05 16:40 [PATCH v3 0/3] introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf Stefano Stabellini
2013-08-05 16:40 ` [PATCH v3 1/3] xen/arm: implement steal_page Stefano Stabellini
2013-08-08 9:55 ` Ian Campbell
2013-08-08 10:37 ` Stefano Stabellini
2013-08-09 15:46 ` Konrad Rzeszutek Wilk
2013-08-14 13:40 ` Stefano Stabellini
2013-08-05 16:40 ` [PATCH v3 2/3] xen: implement guest_physmap_(un)pin_range Stefano Stabellini
2013-08-08 10:52 ` Ian Campbell
2013-08-14 16:08 ` Stefano Stabellini
2013-08-15 14:32 ` Ian Campbell
2013-08-05 16:40 ` [PATCH v3 3/3] xen: introduce XENMEM_get_dma_buf and XENMEM_put_dma_buf Stefano Stabellini
2013-08-08 10:40 ` Ian Campbell
2013-08-08 14:12 ` Keir Fraser
2013-08-08 14:16 ` Stefano Stabellini
2013-08-08 14:26 ` Tim Deegan
2013-08-08 15:04 ` Stefano Stabellini
2013-08-08 14:27 ` Ian Campbell
2013-08-08 14:47 ` Keir Fraser [this message]
2013-08-13 16:05 ` Stefano Stabellini
2013-08-13 22:07 ` Ian Campbell
2013-08-08 11:43 ` Jan Beulich
2013-08-08 14:12 ` Stefano Stabellini
2013-08-08 14:38 ` Jan Beulich
2013-08-08 14:44 ` Stefano Stabellini
2013-08-08 14:50 ` Jan Beulich
2013-08-08 14:54 ` Stefano Stabellini
2013-08-08 14:58 ` Jan Beulich
2013-08-08 15:25 ` Ian Campbell
2013-08-14 16:17 ` Stefano Stabellini
2013-08-15 14:32 ` Ian Campbell
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