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Date:   Wed, 28 Feb 2018 19:17:38 +0200
From:   "Michael S. Tsirkin" <mst@redhat.com>
To:     =?iso-8859-1?Q?Marc-Andr=E9?= Lureau <marcandre.lureau@redhat.com>
Cc:     Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sergio Lopez Pascual <slp@redhat.com>,
        Baoquan He <bhe@redhat.com>, "Somlo, Gabriel" <somlo@cmu.edu>,
        xiaolong.ye@intel.com
Subject: Re: [PATCH v15 11/11] RFC: fw_cfg: do DMA read operation
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On Wed, Feb 28, 2018 at 04:41:51PM +0100, Marc-Andr? Lureau wrote:
> I don't know if it's always safe to enable dma in read_raw(), how
> could we know? Is there a check we could use to choose one or ther
> other (and thus avoiding explicit dma/readfn argument)?

IMHO the way to go is not to try to do zero copy.
Allocate a buffer and DMA there, then copy.

-- 
MST