rust-osdev / rust-osdev/bootloader
`No space left on device` for UEFI image with large kernel image, fixed by increasing FAT padding
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- Rust
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Description
When I try to create a UEFI image with a 600MiB+ kernel image, I sometimes get a No space left on device error.
This can be fixed by altering fat.rs:29:
--- let fat_size_padded_and_rounded = ((needed_size + 1024 * 64 - 1) / MB + 1) * MB + MB;
+++ let fat_size_padded_and_rounded = ((needed_size + 1024 * 64 - 1) / MB + 2) * MB + MB;
to increase the size by 1MiB. I believe this is an issue with clusters and/or fragmentation, but I don't want to just increase a constant and potentially waste that megabyte if I don't need to.
Is there an improved heuristic for the necessary padding and rounding?
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First steps
- Read the whole issue, then the project's contributing guide.
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- Fork the repository and make your change on a branch.
- Open a pull request that references the issue number.
Research direction
Start at fat.rs:29 and reproduce UEFI image creation with a 600MiB+ kernel image. Investigate how FAT clusters or fragmentation affect the required padding and rounding, then verify that the heuristic avoids the No space left on device failure without always wasting an extra MiB.
Written by the indexing model from the issue text.
Assessment
- Tech stack
- rust
- Domain
- operating-systems
- Issue type
- Bug
- Difficulty
- 4/5
- Estimated time
- 3-5 days
- Activity status
- Stale
- Clarity
- Mostly clear
- Newbie friendliness
- 45/100