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. It is not
allowed to specify both 'hostcache' and 'cache' options in the same
commandline.
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
@@ -238,6 +238,7 @@ DriveInfo *drive_init(QemuOpts *opts, in
DriveInfo *dinfo;
int snapshot = 0;
int ret;
+ int hostcache = 0;
translation = BIOS_ATA_TRANSLATION_AUTO;
media = MEDIA_DISK;
@@ -320,7 +321,19 @@ 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;
+ }
+ }
+
if ((buf = qemu_opt_get(opts, "cache")) != NULL) {
+ if (hostcache != -1) {
+ error_report("'hostcache' and 'cache' cannot co-exist");
+ return NULL;
+ }
if (!strcmp(buf, "off") || !strcmp(buf, "none")) {
bdrv_flags |= BDRV_O_NOCACHE | BDRV_O_CACHE_WB;
} else if (!strcmp(buf, "writeback")) {
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|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
@@ -84,6 +84,10 @@ 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 */ }
},
