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. 'cache=xx'
overrides 'hostcache=yy' when specified simultaneously.
Signed-off-by: Supriya Kannery <supri...@linux.vnet.ibm.com>
---
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;
@@ -324,6 +325,12 @@ DriveInfo *drive_init(QemuOpts *opts, in
error_report("invalid cache option");
return NULL;
}
+ } else {
+ if ((hostcache = qemu_opt_get_bool(opts, "hostcache", -1)) != -1) {
+ if (!hostcache) {
+ bdrv_flags |= BDRV_O_NOCACHE;
+ }
+ }
}
#ifdef CONFIG_LINUX_AIO
Index: qemu/qemu-options.hx
===================================================================
--- qemu.orig/qemu-options.hx
+++ qemu/qemu-options.hx
@@ -135,7 +135,7 @@ DEF("drive", HAS_ARG, QEMU_OPTION_drive,
" [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
"
[,cache=writethrough|writeback|none|directsync|unsafe][,format=f]\n"
" [,serial=s][,addr=A][,id=name][,aio=threads|native]\n"
- " [,readonly=on|off]\n"
+ " [,readonly=on|off][,hostcache=on|off]\n"
" use 'file' as a drive image\n", QEMU_ARCH_ALL)
STEXI
@item -drive @var{option}[,@var{option}[,@var{option}[,...]]]
Index: qemu/qemu-config.c
===================================================================
--- qemu.orig/qemu-config.c
+++ qemu/qemu-config.c
@@ -85,6 +85,10 @@ static QemuOptsList qemu_drive_opts = {
.name = "readonly",
.type = QEMU_OPT_BOOL,
.help = "open drive file as read-only",
+ },{
+ .name = "hostcache",
+ .type = QEMU_OPT_BOOL,
+ .help = "set or reset hostcache (on/off)"
},
{ /* end of list */ }
},
