This patch removes support for the cow file format.
Normally we do not break backwards compatibility but in this case there
is no impact and it is the most logical option. Extraordinary claims
require extraordinary evidence so I will show why removing the cow block
driver is the right thing to do.
The cow file format is the disk image format for Usermode Linux, a way
of running a Linux system in userspace. The performance of UML was
never great and it was hacky, but it enjoyed some popularity before
hardware virtualization support became mainstream.
QEMU's block/cow.c is supposed to read this image file format.
Unfortunately the file format was underspecified:
1. Earlier Linux versions used the MAXPATHLEN constant for the backing
filename field. The value of MAXPATHLEN can change, so Linux
switched to a 4096 literal but QEMU has a 1024 literal.
2. Padding was not used on the header struct (both in the Linux kernel
and in QEMU) so the struct layout varied across architectures. In
particular, i386 and x86_64 were different due to int64_t alignment
differences. Linux now uses __attribute__((packed)), QEMU does not.
Therefore:
1. QEMU cow images do not conform to the Linux cow image file format.
2. cow images cannot be shared between different host architectures.
This means QEMU cow images are useless and QEMU has not had bug reports
from users actually hitting these issues.
Let's get rid of this thing, it serves no purpose and no one will be
affected.
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Markus Armbruster <armbru@redhat.com>
Message-id: 1410877464-20481-1-git-send-email-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Refcount structures are placed in clusters randomly selected from all
unallocated host clusters.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Reviewed-by: Fam Zheng <famz@redhat.com>
Message-id: 7e2f38608db6fba2da53997390b19400d445c45d.1408450493.git.maria.k@catit.be
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
If a program under test get frozen, the test should finish and report about its
failure.
In such cases the runner waits for 10 minutes until the program ends its
execution. After this time-out the program will be terminated and the test will
be marked as failed.
For current limitation of test image size to 10 MB as a maximum an execution of
each command takes about several seconds in general, so 10 minutes is enough to
discriminate freeze, but not drastically increase an overall test duration.
Signed-off-by: Maria Kustova <maria.k@catit.be>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
After the specified duration the runner stops executing new tests, but it
doesn't interrupt running ones.
Reviewed-by: Fam Zheng <famz@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Kevin Wolf <kwolf@redhat.com>
Some issues can be found only when a fuzzed image has a partial structure,
e.g. has L1/L2 tables but no refcount ones. Generation of an entirely
defined image limits these cases. Now the Image constructor creates only
a header and a backing file name (if any), other image elements are generated
in the 'create_image' API.
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Entries in L1/L2 entries are based on a portion of random guest clusters.
L2 entries contain offsets to host image clusters filled with random data.
Clusters for L1/L2 tables and guest data are selected randomly.
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
__init__.py provides the public API required by the test runner
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The layout submodule of the qcow2 package creates a random valid image,
randomly selects some amount of its fields, fuzzes them and write the fuzzed
image to the file. Fuzzing process can be controlled by an external
configuration.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The fuzz submodule of the qcow2 image generator contains fuzzing functions for
image fields.
Each fuzzing function contains a list of constraints and a call of a helper
function that randomly selects a fuzzed value satisfied to one of constraints.
For now constraints include only known as invalid or potentially dangerous
values. But after investigation of code coverage by fuzz tests they will be
expanded by heuristic values based on inner checks and flows of a program
under test.
Now fuzzing of a header, header extensions and a backing file name is
supported.
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
The purpose of the test runner is to prepare the test environment (e.g. create
a work directory, a test image, etc), execute a program under test with
parameters, indicate a test failure if the program was killed during the test
execution and collect core dumps, logs and other test artifacts.
The test runner doesn't depend on an image format, so it can be used with any
external image generator.
[Fixed path to qcow2 format module "qcow2" instead of "../qcow2" since
runner.py is no longer in a sub-directory.
--Stefan]
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Maria Kustova <maria.k@catit.be>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
