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Date: Wed, 26 Jun 2013 22:53:32 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] [PATCH] xen_disk: support cache backend option
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To: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: xen-devel@lists.xensource.com, Ian Jackson <Ian.Jackson@eu.citrix.com>, qemu-devel@nongnu.org

Il 26/06/2013 19:48, Stefano Stabellini ha scritto:
> +    if (!strcmp(blkdev->cache, "none")) {
> +        qflags = BDRV_O_NATIVE_AIO | BDRV_O_NOCACHE;
> +    } else if (!strcmp(blkdev->cache, "writethrough")) {
> +        qflags = 0;
> +    } else {
> +        /* default to writeback */
> +        qflags = BDRV_O_NATIVE_AIO | BDRV_O_CACHE_WB;
> +    }

You can use bdrv_parse_cache_flags.  Note that BDRV_O_NATIVE_AIO
requires BDRV_O_NOCACHE too (but if you only specify BDRV_O_NATIVE_AIO
it's a no-op, not an error).

Paolo