mmdebstrap-autopkgtest-build-qemu: add reasons for image being raw and not qcow2

This commit is contained in:
Johannes Schauer Marin Rodrigues 2024-01-30 07:08:56 +01:00
parent 4bcd6fa015
commit e661b79749
Signed by untrusted user: josch
GPG key ID: F2CBA5C78FBD83E1

View file

@ -298,6 +298,16 @@ WORKDIR=$(mktemp -d)
FAT_OFFSET_SECTORS=$((1024*2))
FAT_SIZE_SECTORS=$((1024*254))
# The image is raw and not in qcow2 format because:
# - faster run-time as the "qemu-image convert" step is not needed
# - image can be used independent of qemu tooling
# - modifying the image just with "mount" instead of requiring qemu-nbd
# - sparse images make the file just as small as with qcow2
# - trim support is more difficult on qcow2
# - snapshots and overlays work just as well with raw images
# - users who prefer qcow2 get to choose to run it themselves with their own
# custom options like compression
#
# Make the image writeable to the first subgid. mmdebstrap will map this gid to
# the root group. unshare instead will map the current gid to 0 and the first
# subgid to 1. Therefore mmdebstrap will be able to write to the image.