Patchwork [V5,4/4] Qemu: Add commandline -drive option 'hostcache'

login
register
mail settings
Submitter Supriya Kannery
Date July 27, 2011, 11:31 a.m.
Message ID <20110727113101.25109.41971.sendpatchset@skannery>
Download mbox | patch
Permalink /patch/107034/
State New
Headers show

Comments

Supriya Kannery - July 27, 2011, 11:31 a.m.
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. User has to specify only one among these.

Signed-off-by: Supriya Kannery <supriyak@in.ibm.com>

---
 blockdev.c      |   13 +++++++++++++
 qemu-config.c   |    4 ++++
 qemu-options.hx |    2 +-
 3 files changed, 18 insertions(+), 1 deletion(-)

Patch

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 */ }
     },