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| author | Peter Maydell <peter.maydell@linaro.org> | 2018-03-06 11:20:44 +0000 |
|---|---|---|
| committer | Peter Maydell <peter.maydell@linaro.org> | 2018-03-06 11:20:44 +0000 |
| commit | 58e2e17dba49b43f4ac9de19468aeae1c787dcc2 (patch) | |
| tree | 97b0ec57f56d86b366522544fb7fe577e97b6167 /docs/interop | |
| parent | e1ee9ee139ed7091c2c592d5b784fbb7227bfc0d (diff) | |
| parent | bfe1a14c180ec44c033be12b9151252ffda69292 (diff) | |
| download | focaccia-qemu-58e2e17dba49b43f4ac9de19468aeae1c787dcc2.tar.gz focaccia-qemu-58e2e17dba49b43f4ac9de19468aeae1c787dcc2.zip | |
Merge remote-tracking branch 'remotes/kevin/tags/for-upstream' into staging
Block layer patches # gpg: Signature made Mon 05 Mar 2018 17:45:51 GMT # gpg: using RSA key 7F09B272C88F2FD6 # gpg: Good signature from "Kevin Wolf <kwolf@redhat.com>" # Primary key fingerprint: DC3D EB15 9A9A F95D 3D74 56FE 7F09 B272 C88F 2FD6 * remotes/kevin/tags/for-upstream: (38 commits) block: Fix NULL dereference on empty drive error qcow2: Replace align_offset() with ROUND_UP() block/ssh: Add basic .bdrv_truncate() block/ssh: Make ssh_grow_file() blocking block/ssh: Pull ssh_grow_file() from ssh_create() qemu-img: Make resize error message more general qcow2: make qcow2_co_create2() a coroutine_fn block: rename .bdrv_create() to .bdrv_co_create_opts() Revert "IDE: Do not flush empty CDROM drives" block: test blk_aio_flush() with blk->root == NULL block: add BlockBackend->in_flight counter block: extract AIO_WAIT_WHILE() from BlockDriverState aio: rename aio_context_in_iothread() to in_aio_context_home_thread() docs: document how to use the l2-cache-entry-size parameter specs/qcow2: Fix documentation of the compressed cluster descriptor iotest 033: add misaligned write-zeroes test via truncate block: fix write with zero flag set and iovector provided block: Drop unused .bdrv_co_get_block_status() vvfat: Switch to .bdrv_co_block_status() vpc: Switch to .bdrv_co_block_status() ... Signed-off-by: Peter Maydell <peter.maydell@linaro.org> # Conflicts: # include/block/block.h
Diffstat (limited to 'docs/interop')
| -rw-r--r-- | docs/interop/qcow2.txt | 16 |
1 files changed, 13 insertions, 3 deletions
diff --git a/docs/interop/qcow2.txt b/docs/interop/qcow2.txt index d7fdb1fee3..feb711fb6a 100644 --- a/docs/interop/qcow2.txt +++ b/docs/interop/qcow2.txt @@ -426,10 +426,20 @@ Standard Cluster Descriptor: Compressed Clusters Descriptor (x = 62 - (cluster_bits - 8)): - Bit 0 - x: Host cluster offset. This is usually _not_ aligned to a - cluster boundary! + Bit 0 - x-1: Host cluster offset. This is usually _not_ aligned to a + cluster or sector boundary! - x+1 - 61: Compressed size of the images in sectors of 512 bytes + x - 61: Number of additional 512-byte sectors used for the + compressed data, beyond the sector containing the offset + in the previous field. Some of these sectors may reside + in the next contiguous host cluster. + + Note that the compressed data does not necessarily occupy + all of the bytes in the final sector; rather, decompression + stops when it has produced a cluster of data. + + Another compressed cluster may map to the tail of the final + sector used by this compressed cluster. If a cluster is unallocated, read requests shall read the data from the backing file (except if bit 0 in the Standard Cluster Descriptor is set). If there is |