On 2025-06-26 01:08, Pascal Hambourg wrote:
[The mail I am replying to was sent to the bug but was not forwarded
to the list for some reason, although its size of 98ko is much smaller
than the previously observed limit of ~450-500ko. You can see it and
its attached screenshot at
<https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=1106757#120>]
On 25/06/2025 at 09:50, Trupti wrote:
On 2025-06-23 20:58, Trupti wrote:
To complete the end-to-end test scenario, I am now creating test
files
on the Bookworm partitions.
I will proceed with the Trixie installation, manually preserving the
partitions, and will then verify the files are intact in the new
system. I will post the final results of this data integrity test
here
soon.
(...)
You were absolutely right — I’ve completed the testing as suggested.
I tested ext4 (4K & 64K) and Btrfs partitions between Bookworm (64K
kernel) and Trixie (4K kernel), and the following behavior was
observed:
1]ext4 partitions with 4K block size worked fine — existing files
were accessible without issues.
2]ext4 (64K) and Btrfs partitions couldn’t be mounted in Trixie
(showed a "Mount Failed" error),
and the installer failed unless those partitions were formatted.
ext4 with a 4K block size is compatible across both kernels. However,
partitions created with a 64K block size (ext4 or Btrfs) are not
supported by the 4K kernel. These need to be formatted during
installation, which can lead to potential data loss.
To sum it up:
- With bookworm d-i and installed system 64k page size kernel,
mkfs.btrfs with default options and mke2fs -T largefile|largefile4
create filesystems with 64k block size.
- With trixie d-i 4k page size kernel, btrfs and ext* with 64k block
size filesystems are not supported and cannot be reused without being
reformatted with 4k block size (and losing data).
Shouldn't it at least be mentioned in ppc64el installation manual ?
Yes, I agree — this behavior should definitely be documented in the
ppc64el installation manual, especially to warn users about the
incompatibility and potential data loss when using ext4 or Btrfs
filesystems with 64k block size on a 4k page-size kernel.
Also, summarizing our discussion here regarding feasible solutions for
users who want to install a 64k page-size kernel from the beginning:
One possible option is to provide a dedicated official 64k ISO for
ppc64el.
Another approach could be to include both 4k and 64k kernel variants
in the same ISO, allowing users to select the preferred option from
the boot menu — similar to what was done in older multi-arch
amd64+i386 images.
I kindly request the Debian Installer team to consider implementing
one of these installation options for Debian on PowerPC, so that users
who require a 64k setup can install it safely and directly.
Thanks Trupti