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Re: [Qemu-devel] [PATCH v2] xen_disk: add discard support
From: |
Stefano Stabellini |
Subject: |
Re: [Qemu-devel] [PATCH v2] xen_disk: add discard support |
Date: |
Thu, 20 Feb 2014 18:06:25 +0000 |
User-agent: |
Alpine 2.02 (DEB 1266 2009-07-14) |
On Thu, 6 Feb 2014, Olaf Hering wrote:
> @@ -253,6 +254,8 @@ static int ioreq_parse(struct ioreq *ioreq)
> case BLKIF_OP_WRITE:
> ioreq->prot = PROT_READ; /* from memory */
> break;
> + case BLKIF_OP_DISCARD:
> + return 0;
> default:
> xen_be_printf(&blkdev->xendev, 0, "error: unknown operation (%d)\n",
> ioreq->req.operation);
Unfortunately I didn't realize before that older Xen releases don't
define BLKIF_OP_DISCARD, therefore this patch would cause QEMU build
failures against Xen 4.1 for example.
Give a look at include/hw/xen/xen_common.h to see how compatibility
with older Xen versions is usually achieved in QEMU.