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-rw-r--r--vl.c18
1 files changed, 12 insertions, 6 deletions
diff --git a/vl.c b/vl.c
index 97aca75179..c0e43ac030 100644
--- a/vl.c
+++ b/vl.c
@@ -5648,10 +5648,12 @@ static int drive_init(struct drive_opt *arg, int snapshot,
}
if (get_param_value(buf, sizeof(buf), "cache", str)) {
- if (!strcmp(buf, "off"))
+ if (!strcmp(buf, "off") || !strcmp(buf, "none"))
cache = 0;
- else if (!strcmp(buf, "on"))
+ else if (!strcmp(buf, "writethrough"))
cache = 1;
+ else if (!strcmp(buf, "writeback"))
+ cache = 2;
else {
fprintf(stderr, "qemu: invalid cache option\n");
return -1;
@@ -5770,10 +5772,14 @@ static int drive_init(struct drive_opt *arg, int snapshot,
if (!file[0])
return 0;
bdrv_flags = 0;
- if (snapshot)
+ if (snapshot) {
bdrv_flags |= BDRV_O_SNAPSHOT;
- if (!cache)
- bdrv_flags |= BDRV_O_DIRECT;
+ cache = 2; /* always use write-back with snapshot */
+ }
+ if (cache == 0) /* no caching */
+ bdrv_flags |= BDRV_O_NOCACHE;
+ else if (cache == 2) /* write-back */
+ bdrv_flags |= BDRV_O_CACHE_WB;
if (bdrv_open2(bdrv, file, bdrv_flags, drv) < 0 || qemu_key_check(bdrv, file)) {
fprintf(stderr, "qemu: could not open disk image %s\n",
file);
@@ -8145,7 +8151,7 @@ static void help(int exitcode)
"-cdrom file use 'file' as IDE cdrom image (cdrom is ide1 master)\n"
"-drive [file=file][,if=type][,bus=n][,unit=m][,media=d][,index=i]\n"
" [,cyls=c,heads=h,secs=s[,trans=t]][,snapshot=on|off]\n"
- " [,cache=on|off][,format=f]\n"
+ " [,cache=writethrough|writeback|none][,format=f]\n"
" use 'file' as a drive image\n"
"-mtdblock file use 'file' as on-board Flash memory image\n"
"-sd file use 'file' as SecureDigital card image\n"