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Re: [Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'host
From: |
Kevin Wolf |
Subject: |
Re: [Qemu-devel] [v7 Patch 4/5]Qemu: Add commandline -drive option 'hostcache' |
Date: |
Wed, 12 Oct 2011 16:30:45 +0200 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:7.0) Gecko/20110927 Thunderbird/7.0 |
Am 11.10.2011 05:11, schrieb Supriya Kannery:
> qemu command option 'hostcache' added to -drive for block devices.
> While starting a VM from qemu commandline, this option can be used
> for setting host cache usage for block data access. Simultaneous
> use of 'hostcache' and 'cache' options not allowed.
>
> Signed-off-by: Supriya Kannery <address@hidden>
I'm not sure if introducing this alone makes sense. I think I would only
do it when we introduce more options that allow replacing all cache=...
options by other parameters.
>
> ---
> blockdev.c | 13 +++++++++++++
> qemu-config.c | 4 ++++
> qemu-options.hx | 2 +-
> 3 files changed, 18 insertions(+), 1 deletion(-)
>
> Index: qemu/blockdev.c
> ===================================================================
> --- qemu.orig/blockdev.c
> +++ qemu/blockdev.c
> @@ -237,6 +237,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
> DriveInfo *dinfo;
> int snapshot = 0;
> int ret;
> + int hostcache = 0;
>
> translation = BIOS_ATA_TRANSLATION_AUTO;
> media = MEDIA_DISK;
> @@ -319,7 +320,19 @@ DriveInfo *drive_init(QemuOpts *opts, in
> }
> }
>
> + if ((hostcache = qemu_opt_get_bool(opts, "hostcache", -1)) != -1) {
> + if (!hostcache) {
> + bdrv_flags |= BDRV_O_NOCACHE;
> + } else {
> + bdrv_flags &= ~BDRV_O_NOCACHE;
> + }
bdrv_flags is initialised to 0, so the else branch is unnecessary.
Kevin