58296b3376
Records the direction set out today -- snapshots, scrub, compression and encryption for SchFS; one shared home for the format; a unified second stage under both firmwares; audio -- and the two requests that were pushed back on, with the reasoning, so neither gets re-litigated from scratch: 128-bit addressing buys nothing over the 64 ZB already addressable, and SchFS cannot live in projects/ because the kernel has to mount it to boot. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
67 lines
3.3 KiB
Markdown
67 lines
3.3 KiB
Markdown
---
|
|
name: schfs-next-and-platform-roadmap
|
|
description: "The 2026-08-10 direction — SchFS features, one shared home for the format, a unified loader, audio; and the two requests that were pushed back on"
|
|
metadata:
|
|
node_type: memory
|
|
type: project
|
|
originSessionId: d4821aa9-2e49-40da-91e7-90ef9ed9997e
|
|
modified: 2026-08-10T16:52:05.449Z
|
|
---
|
|
|
|
**Set out by Nexoniarz 2026-08-10**, after the compositor and resolution work.
|
|
|
|
## Two requests that were pushed back on, and why
|
|
|
|
**"Make SchFS bigger than ZFS."** Declined as stated, and Nexoniarz did not
|
|
press it. SchFS already addresses **64 ZB** (64-bit block numbers at 4 KB).
|
|
ZFS is 128-bit — a number its designers said could not be filled without
|
|
boiling the oceans. Beating it means 128-bit block pointers: every pointer in
|
|
the B-tree doubles, cache pressure with it, for a limit already physically
|
|
unreachable. A spec-sheet win with a real cost.
|
|
|
|
**"Move SchFS to projects/."** Cannot be done as stated: `projects/` is for
|
|
things that run *on* SchOS, never linking kernel headers and never a dependency
|
|
of the kernel build ([[schunix-roadmap-and-projects]]). SchFS is the root
|
|
filesystem — the kernel must mount it to boot. **The version that works** is a
|
|
neutral `lib/schfs/` consumed by the kernel, by `mkschfs`/`schfs_fsck`, and by
|
|
`projects/schfs-linux`. The source is *already* shared verbatim; this only moves
|
|
where it lives. Agreed as the sensible form, not yet done.
|
|
|
|
## Done 2026-08-10: the ceiling that actually existed
|
|
|
|
The format said 64 ZB; the stack under it said **614 MB**. `idestart` panicked
|
|
on any block past `FSSIZE` (150000 blocks) — a constant describing a v1
|
|
filesystem *image*, bounding a physical device. Fixed in commit 527e6ea along
|
|
with the rest of the chain: `struct buf.blockno` and `bread` are 64-bit,
|
|
sectors are computed in 64 bits, and LBA48 is used per request when the sector
|
|
does not fit in 28 bits.
|
|
|
|
**Still capped, deliberately:** raw `/dev/hdN` goes through devsw's 32-bit
|
|
offset, so a raw device is addressable to **4 GB**; `usb_storage` builds a
|
|
32-bit LBA, which is what SCSI READ(10) carries — READ(16) is a different
|
|
command, not a wider variable.
|
|
|
|
## The SchFS feature list, all four wanted
|
|
|
|
Nexoniarz asked for all of these. Suggested order is mine, cheapest and
|
|
highest-leverage first:
|
|
|
|
1. **Snapshots and clones.** The copy-on-write B-tree already makes a snapshot
|
|
a retained tree root ([[schfs-btree-phase1]]). Almost certainly the best
|
|
value per unit of work on the list.
|
|
2. **Integrity: scrub, repair, redundancy.** CRC32c per data block already
|
|
exists; this is detecting and *repairing* rather than only reporting —
|
|
duplicate metadata, a scrub pass.
|
|
3. **Compression**, per extent. The extent record already carries a length and
|
|
a disk block, so there is somewhere to put a compressed size.
|
|
4. **Encryption.** Confidentiality, where the checksums give integrity. Last
|
|
because it is the one with the most ways to be subtly wrong.
|
|
|
|
## The platform list
|
|
|
|
- **A unified second stage.** BIOS and UEFI become thin starters handing off to
|
|
one common loader. This is worth real money: the duplication is exactly what
|
|
produced the `EFER.SCE` and RSDP bugs, where the BIOS path had something the
|
|
UEFI path silently did not ([[schos-uefi-loader]]).
|
|
- **Audio.** First sound driver, new device class. Intel HDA or AC'97 — both
|
|
emulated by QEMU, both with public specs.
|