The null driver is very usefull for testing and benchmarking, but it can not emulate an image full of zeroes or an image full of non-zero bytes. Such images are needed for testing computing a blkhash via qemu-nbd or qemu-storage-daemon.
This change adds `read-pattern` option allowing emulution of image full of zeroes and image for of non-zero bytes. I used this for testing https://lists.gnu.org/archive/html/qemu-devel/2025-04/msg05096.html Changes since v1: - Make read-zeroes and read-pattern mutual exclusive [Eric, Markus] - Narrow read-pattern type to uint8 [Eric, Markus] - Update the doc comment to explain that read-zeroes emulates a sparsse image, and read-pattern emulates an allocated image. [Markus] - Validate that read-pattern value is within range - Update secure-coding-practices guide with read-pattern option v1 was here: https://lists.gnu.org/archive/html/qemu-devel/2025-04/msg05098.html Nir Soffer (2): block/null: Report DATA if not reading zeroes block/null: Add read-pattern option block/null.c | 38 +++++++++++++++++++++++--- docs/devel/secure-coding-practices.rst | 3 +- qapi/block-core.json | 17 ++++++++++-- 3 files changed, 50 insertions(+), 8 deletions(-) -- 2.39.5 (Apple Git-154)
