qcow2: Add incompatibility note between backing files and raw external data files

qemu with hax to log dma reads & writes jcs.org/2018/11/12/vfio

Backing files and raw external data files are mutually exclusive.
The documentation of the raw external data bit (in autoclear_features)
already indicates that, but we should also mention it on the other
side.

Suggested-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Alberto Garcia <berto@igalia.com>
Message-Id: <20200410121816.8334-1-berto@igalia.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>

authored by

Alberto Garcia and committed by

Kevin Wolf 5 years ago a50c1f57 16aaacb3

1 changed file

expand all

docs

interop

qcow2.txt

docs/interop/qcow2.txt

··· 25 25 is stored (NB: The string is not null terminated). 0 if the 26 26 image doesn't have a backing file. 27 27 28 + Note: backing files are incompatible with raw external data 29 + files (auto-clear feature bit 1). 30 + 28 31 16 - 19: backing_file_size 29 32 Length of the backing file name in bytes. Must not be 30 33 longer than 1023 bytes. Undefined if the image doesn't have