Summary
Please enable the userspace block driver (ublk) as a loadable module —
CONFIG_BLK_DEV_UBLK=m — in the Amazon Linux 2027 kernel. It is currently disabled in the
AL2027 preview (kernel 7.1):
# CONFIG_BLK_DEV_UBLK is not set
Related
This mirrors amazonlinux/amazon-linux-2023#1077, where the Amazon Linux team indicated they
would "likely enable it starting from kernels 6.18." AL2027 ships kernel 7.1 (> 6.18), so
this request is to confirm AL2027 is included in that change and to track it in the
AL2027 tracker.
Use case
A userspace block device workload built on ublk — the io_uring-based framework for
implementing block devices in userspace via ublksrv. It's the modern, high-performance
successor to NBD/TCMU-style approaches for custom storage backends and disaggregated/network
storage frontends. Without the in-tree module enabled, AL2027 requires an out-of-tree module
build on every host.
Requested change
For both x86_64 and aarch64. Enabling during the preview window is strongly preferred so
it's present at GA.
Impact / risk
- Tristate module — compiled, not loaded by default → no boot-time, memory, or
attack-surface cost on hosts that don't use it.
- Mainline since 6.0, actively maintained; AL2027's 7.1 source already contains the
driver (drivers/block/ublk_drv.c).
- Depends only on
io_uring/block infrastructure already enabled in the AL kernel.
- Already enabled as a module in other Amazon-built kernels.
Verified workaround (in the meantime)
Confirmed on AL2027 (kernel 7.1.0-88.111.amzn2027.x86_64) that the in-tree driver builds
cleanly out-of-tree, loads (unsigned, kernel taint — Secure Boot off, CONFIG_MODULE_SIG_FORCE
not set), and runs end-to-end with ublksrv (null + loop targets, filesystem write/read
verified). Full runbook, including a DKMS package that survives kernel upgrades:
https://gist.github.com/rndjams/fae438dbbc1780443b0170693803719e
Note: the module must be loaded from /lib/modules/<kver>/extra (correct SELinux label under
enforcing=1), not from a home directory.
Summary
Please enable the userspace block driver (
ublk) as a loadable module —CONFIG_BLK_DEV_UBLK=m— in the Amazon Linux 2027 kernel. It is currently disabled in theAL2027 preview (kernel 7.1):
Related
This mirrors amazonlinux/amazon-linux-2023#1077, where the Amazon Linux team indicated they
would "likely enable it starting from kernels 6.18." AL2027 ships kernel 7.1 (> 6.18), so
this request is to confirm AL2027 is included in that change and to track it in the
AL2027 tracker.
Use case
A userspace block device workload built on
ublk— the io_uring-based framework forimplementing block devices in userspace via
ublksrv. It's the modern, high-performancesuccessor to NBD/TCMU-style approaches for custom storage backends and disaggregated/network
storage frontends. Without the in-tree module enabled, AL2027 requires an out-of-tree module
build on every host.
Requested change
For both
x86_64andaarch64. Enabling during the preview window is strongly preferred soit's present at GA.
Impact / risk
attack-surface cost on hosts that don't use it.
driver (
drivers/block/ublk_drv.c).io_uring/block infrastructure already enabled in the AL kernel.Verified workaround (in the meantime)
Confirmed on AL2027 (kernel
7.1.0-88.111.amzn2027.x86_64) that the in-tree driver buildscleanly out-of-tree, loads (unsigned, kernel taint — Secure Boot off,
CONFIG_MODULE_SIG_FORCEnot set), and runs end-to-end with
ublksrv(null + loop targets, filesystem write/readverified). Full runbook, including a DKMS package that survives kernel upgrades:
https://gist.github.com/rndjams/fae438dbbc1780443b0170693803719e
Note: the module must be loaded from
/lib/modules/<kver>/extra(correct SELinux label underenforcing=1), not from a home directory.