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…i-extent reads
This adds basic ext4 support to aboot so it can mount and read modern ext4
filesystems commonly found on Alpha systems.
Key features:
- 64-byte ext4 group descriptor support (using sb.s_desc_size)
- Accept and whitelist common ext4 INCOMPAT/RO_COMPAT flags:
64bit, flex_bg, mmp, csum_seed, metadata_csum
- Implement multi-extent reading for inline extents (eh_depth == 0)
- Clamp reads to i_size to avoid out-of-range extent lookups
With these changes aboot can successfully mount ext4 partitions and load
kernels stored in files using multiple inline extents. Full extent-tree
support (non-zero eh_depth) and full 64-bit block handling remain future
work.
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
The following patch is a modified version of the patch written by j.j.vanderheijden@home.nl and allows aboot to handle XFS partitions. It has been tested against a Digital Personal Workstation and seems to work just fine. (patch modifications by Mike Hlavac)
debug output. This code does not work at the moment.
Fix two bugs in the XFS directory reader that prevented aboot from
finding files on XFS v4 (crc=0) filesystems:
- Add missing read of the 4-byte DIR2 entry header. Without this,
freetag/length values were uninitialized, causing corrupted
filenames and incorrect directory offsets.
- Skip nameless/invalid entries to avoid returning garbage names.
With these fixes, aboot can reliably load files from classic XFS v4
(naming version 2, no CRC). Modern CRC-enabled (v5) XFS filesystems
remain unsupported.
Signed-off-by: Magnus Lindholm <linmag7@gmail.com>
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This pull request adds EXT4 boot support and updates the existing XFS boot
support code. It includes four commits, tagged as:
Summary of changes
descriptor handling.