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authorChristoph Hellwig <hch@lst.de>2009-09-04 19:01:15 +0200
committerAnthony Liguori <aliguori@us.ibm.com>2009-09-11 10:19:46 -0500
commite900a7b748316b5b5a98e41dde36a0cb8e15be5f (patch)
treef41d52f388664258f5caa4a03645cb4409676065 /hw/ide/core.c
parentb8193adbda922659ba290fd9fb6ee053ee191d70 (diff)
downloadfocaccia-qemu-e900a7b748316b5b5a98e41dde36a0cb8e15be5f.tar.gz
focaccia-qemu-e900a7b748316b5b5a98e41dde36a0cb8e15be5f.zip
block: add enable_write_cache flag
Add a enable_write_cache flag in the block driver state, and use it to
decide if we claim to have a volatile write cache that needs controlled
flushing from the guest.  The flag is off if cache=writethrough is
defined because O_DSYNC guarantees that every write goes to stable
storage, and it is on for cache=none and cache=writeback.

Both scsi-disk and ide now use the new flage, changing from their
defaults of always off (ide) or always on (scsi-disk).

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>
Diffstat (limited to 'hw/ide/core.c')
-rw-r--r--hw/ide/core.c7
1 files changed, 5 insertions, 2 deletions
diff --git a/hw/ide/core.c b/hw/ide/core.c
index fe5bd172af..6fd6dc2477 100644
--- a/hw/ide/core.c
+++ b/hw/ide/core.c
@@ -148,8 +148,11 @@ static void ide_identify(IDEState *s)
     put_le16(p + 83, (1 << 14) | (1 << 13) | (1 <<12) | (1 << 10));
     /* 14=set to 1, 1=SMART self test, 0=SMART error logging */
     put_le16(p + 84, (1 << 14) | 0);
-    /* 14 = NOP supported, 0=SMART feature set enabled */
-    put_le16(p + 85, (1 << 14) | 1);
+    /* 14 = NOP supported, 5=WCACHE enabled, 0=SMART feature set enabled */
+    if (bdrv_enable_write_cache(s->bs))
+         put_le16(p + 85, (1 << 14) | (1 << 5) | 1);
+    else
+         put_le16(p + 85, (1 << 14) | 1);
     /* 13=flush_cache_ext,12=flush_cache,10=lba48 */
     put_le16(p + 86, (1 << 14) | (1 << 13) | (1 <<12) | (1 << 10));
     /* 14=set to 1, 1=smart self test, 0=smart error logging */