abi: reserve 48 KiB for valid fork continuations#954
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The fixed 16 KiB save buffer rejects valid wide fork call chains: the Homebrew launcher needs 20,012 bytes and GTK/GLib needs 21,544 bytes. Reserve 48 KiB within the existing 64 KiB main and pthread scratch pages, and apply the same bound to side modules. Publish the incompatible address/layout change as ABI 40, regenerate the snapshot and generated host/libc constants, and keep truthful overrun detection above the new capacity.
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The automatic exact-head staging run was intentionally cancelled after preflight. This source PR changes ABI 40, but it is not the merge unit: rebuilding its incomplete package universe would be discarded when the final ABI 40 batch adds the remaining reviewed source commits. The final batch must run the one authoritative package-universe, Node/browser, conformance, and Homebrew bootstrap build. |
Phase B-1 matrix build status —
|
| Package | Arch | Status | Sha |
|---|---|---|---|
| icu | wasm32 | failed | — |
| libcurl | wasm32 | failed | — |
| libcxx | wasm32 | failed | — |
| libcxx | wasm64 | failed | — |
| libiconv | wasm32 | failed | — |
| libpng | wasm32 | failed | — |
| libxml2 | wasm32 | failed | — |
| libzip | wasm32 | failed | — |
| openssl | wasm32 | failed | — |
| openssl | wasm64 | failed | — |
| sqlite | wasm32 | failed | — |
| sqlite | wasm64 | failed | — |
| zlib | wasm32 | failed | — |
| zlib | wasm64 | failed | — |
| bc | wasm32 | failed | — |
| bzip2 | wasm32 | failed | — |
| coreutils | wasm32 | failed | — |
| curl | wasm32 | failed | — |
| dash | wasm32 | failed | — |
| diffutils | wasm32 | failed | — |
| dinit | wasm32 | failed | — |
| fbdoom | wasm32 | failed | — |
| file | wasm32 | failed | — |
| findutils | wasm32 | failed | — |
| gawk | wasm32 | failed | — |
| git | wasm32 | failed | — |
| grep | wasm32 | failed | — |
| gzip | wasm32 | failed | — |
| hello | wasm32 | failed | — |
| kandelo-sdk | wasm32 | failed | — |
| kernel | wasm32 | failed | — |
| less | wasm32 | failed | — |
| lsof | wasm32 | failed | — |
| m4 | wasm32 | failed | — |
| make | wasm32 | failed | — |
| mariadb | wasm32 | failed | — |
| mariadb | wasm64 | failed | — |
| modeset | wasm32 | failed | — |
| msmtpd | wasm32 | failed | — |
| nano | wasm32 | failed | — |
| ncurses | wasm32 | failed | — |
| netcat | wasm32 | failed | — |
| nginx | wasm32 | failed | — |
| php | wasm32 | failed | — |
| posix-utils-lite | wasm32 | failed | — |
| ruby | wasm32 | failed | — |
| sed | wasm32 | failed | — |
| spidermonkey | wasm32 | failed | — |
| tar | wasm32 | failed | — |
| tcl | wasm32 | failed | — |
| unzip | wasm32 | failed | — |
| userspace | wasm32 | failed | — |
| vim | wasm32 | failed | — |
| wget | wasm32 | failed | — |
| xz | wasm32 | failed | — |
| zip | wasm32 | failed | — |
| zstd | wasm32 | failed | — |
| bash | wasm32 | failed | — |
| mariadb-test | wasm32 | failed | — |
| mariadb-vfs | wasm32 | failed | — |
| mariadb-vfs | wasm64 | failed | — |
| nethack | wasm32 | failed | — |
| node | wasm32 | failed | — |
| spidermonkey-node | wasm32 | failed | — |
| vim-browser-bundle | wasm32 | failed | — |
| nethack-browser-bundle | wasm32 | failed | — |
| rootfs | wasm32 | failed | — |
| shell | wasm32 | failed | — |
| lamp | wasm32 | failed | — |
| node-vfs | wasm32 | failed | — |
| wordpress | wasm32 | failed | — |
Auto-generated; replaced on each push. Raw data in the publish-status workflow artifact.
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Why
When a process calls
fork, Kandelo saves enough instrumented WebAssembly call-frame data to resume the child at the same point. That saved data is the fork continuation, and the reserved linear-memory region that holds it is the fork save buffer. KiB means 1,024 bytes.Kandelo's truthful fork-overrun guard is rejecting valid real application continuations because every main-thread, pthread, and side-module fork save buffer is fixed at 16 KiB.
Measured production paths already exceed that reserve:
/usr/bin/brewalias launcherThe existing guard correctly prevents those writes from becoming channel or control-state corruption, but Homebrew and GTK cannot complete valid forks at the current capacity.
What changed
dlopenarchive anchor.This is a platform capacity correction, not a Homebrew-specific bypass. All ABI-bound programs, package archives, and VFS images must be rebuilt through the normal ABI 40 release path; this source PR must not be merged separately from that train.
When the ABI 40 integration batch combines this change with #944, it must also update #944's bootstrap probe and documentation to require a successful
brew --versioninstead of accepting the historical ABI 39 reserve failure. Those files do not exist on this source branch because #944 has not merged.Validation
Run through
scripts/dev-shell.shon exact commit27b37930f3a1ebc57017973d3cd74c6ddedce415/ treedacd6b77055ad3732d1219eeb80212b8dac62970:scripts/check-abi-version.shpassed and confirmed the ABI bump plus synchronized snapshot/generated bindings;git diff --check origin/main...HEADpassed.The complete fork-instrument suite passed on this exact head (186 tests).
Host declaration generation was attempted on the predecessor, but the isolated source worktree has no installed
host/node_modules, sotsupwas unavailable. Full host, browser, libc, POSIX, Sortix, package-universe, and rebuilt Homebrew bootstrap validation is intentionally assigned to the broad ABI 40 batch that absorbs this exact source commit.