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| author | Stefan Hajnoczi <stefanha@linux.vnet.ibm.com> | 2012-07-27 09:05:20 +0100 |
|---|---|---|
| committer | Kevin Wolf <kwolf@redhat.com> | 2012-08-06 22:39:14 +0200 |
| commit | dae8796d009ffc4d980db1f87f26eed0074be4ef (patch) | |
| tree | ad11363b1a7ce0ad52b854edeb653ad657fc7fbb /docs/specs | |
| parent | c61d0004bc37182cae0f92a865ad2f0625762610 (diff) | |
| download | qemu-dae8796d009ffc4d980db1f87f26eed0074be4ef.zip qemu-dae8796d009ffc4d980db1f87f26eed0074be4ef.tar.gz qemu-dae8796d009ffc4d980db1f87f26eed0074be4ef.tar.bz2 | |
docs: add lazy refcounts bit to qcow2 specification
The lazy refcounts bit indicates that this image can take advantage of
the dirty bit and that refcount updates can be postponed.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Diffstat (limited to 'docs/specs')
| -rw-r--r-- | docs/specs/qcow2.txt | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/docs/specs/qcow2.txt b/docs/specs/qcow2.txt index 339cdc1..36a559d 100644 --- a/docs/specs/qcow2.txt +++ b/docs/specs/qcow2.txt @@ -86,7 +86,12 @@ in the description of a field. Bitmask of compatible features. An implementation can safely ignore any unknown bits that are set. - Bits 0-63: Reserved (set to 0) + Bit 0: Lazy refcounts bit. If this bit is set then + lazy refcount updates can be used. This means + marking the image file dirty and postponing + refcount metadata updates. + + Bits 1-63: Reserved (set to 0) 88 - 95: autoclear_features Bitmask of auto-clear features. An implementation may only |