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Message-ID: <20150427111729.06a9492e.cornelia.huck@de.ibm.com>
Date: Mon, 27 Apr 2015 11:17:29 +0200
From: Cornelia Huck <cornelia.huck@...ibm.com>
To: Greg Kurz <gkurz@...ux.vnet.ibm.com>
Cc: Rusty Russell <rusty@...tcorp.com.au>,
"Michael S. Tsirkin" <mst@...hat.com>,
Thomas Huth <thuth@...hat.com>, kvm@...r.kernel.org,
linux-api@...r.kernel.org, linux-kernel@...r.kernel.org,
virtualization@...ts.linux-foundation.org
Subject: Re: [PATCH v6 7/8] vhost: cross-endian support for legacy devices
On Fri, 24 Apr 2015 14:27:24 +0200
Greg Kurz <gkurz@...ux.vnet.ibm.com> wrote:
> This patch brings cross-endian support to vhost when used to implement
> legacy virtio devices. Since it is a relatively rare situation, the
> feature availability is controlled by a kernel config option (not set
> by default).
>
> The vq->is_le boolean field is added to cache the endianness to be
> used for ring accesses. It defaults to native endian, as expected
> by legacy virtio devices. When the ring gets active, we force little
> endian if the device is modern. When the ring is deactivated, we
> revert to the native endian default.
>
> If cross-endian was compiled in, a vq->user_be boolean field is added
> so that userspace may request a specific endianness. This field is
> used to override the default when activating the ring of a legacy
> device. It has no effect on modern devices.
>
> Signed-off-by: Greg Kurz <gkurz@...ux.vnet.ibm.com>
> ---
>
> Changes since v5:
> - fixed description in Kconfig
> - fixed error description in uapi header
> - dropped useless semi-colon in the vhost_vq_reset_user_be() stub
>
> drivers/vhost/Kconfig | 15 ++++++++
> drivers/vhost/vhost.c | 85 +++++++++++++++++++++++++++++++++++++++++++-
> drivers/vhost/vhost.h | 11 +++++-
> include/uapi/linux/vhost.h | 14 +++++++
> 4 files changed, 122 insertions(+), 3 deletions(-)
>
Reviewed-by: Cornelia Huck <cornelia.huck@...ibm.com>
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