QUERY · ISSUE

Block device `readblock(8, 44)` before `ioctl(1)` for `os.mount(block_device, ...)`

openby pulkinopened 2023-03-07updated 2023-03-07

bug

According to docs, a block device interface may implement ioctl(1) "initialize the device". In practice, os.mount(block_device, ...) reads 44 bytes with offset 8 without bothering to call ioctl(1) first. It is probably the auto-detect feature FAT vs littlefs.

CANDIDATE · PULL REQUEST

os.rst: Clarify littlefs requirements.

closedby peterhinchopened 2021-09-07updated 2021-09-10

docs

The doc detailing the need to intercept the erase block ioctl call is ambiguous as evidenced by this thread.

This edit is based on inference from test scripts and docs rather than detailed knowledge of littlefs - please check!

Assessment

Q Qwen · medium

Issue #10963 reports a bug where os.mount() calls readblock(8, 44) before ioctl(1), violating the documented block device interface contract. PR #7755 is a documentation update clarifying littlefs requirements regarding ioctl calls, specifically mentioning that ioctl(6, block) is issued before writeblocks(). While both items concern block device initialization and ioctl calls, PR #7755 only addresses documentation for littlefs and doesn't fix the actual bug in the mount sequence where readblock is called before ioctl(1). The PR provides context about ioctl usage but doesn't resolve the reported issue.

Suggested action

Keep issue #10963 open. The documentation update in PR #7755 is helpful context but doesn't fix the underlying bug. Consider creating a new PR to fix the mount sequence to call ioctl(1) before readblock(8, 44) as documented.

Block device `readblock(8, 44)` before `ioctl(1)` for `os.mount(block_device, ...)`

os.rst: Clarify littlefs requirements.

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