lukaszraczylo
b26afa2a5d
Replaces snapshot-of-tx_tail comparison in the watchdog with a tx_stall_tail_moved flag set/cleared under tx_ptr_lock. Avoids the index-aliasing false-positive Phil Elwell flagged on the raspberrypi/linux PR review. Anchored against the rpi-6.18.y vendor fork so it applies cleanly on top of patches 0001..0003. See talos-kernel-patches/0004-*.patch for the mainline-anchored variant intended for netdev v2.
Local kernel patches
Drop-in .patch files copied into pkgs/kernel/build/patches/ at build time by the patches-linux Makefile target. Filenames sort lexicographically; the kernel build script in pkgs applies them in that order with patch -p1.
Current series — 0001..0003-net-macb
Three patches addressing the silent TX stall on Raspberry Pi 5 (BCM2712 + RP1 PCIe south bridge, Cadence GEM via macb). Same series posted to the Linux netdev mailing list as [RFC PATCH net-next 0/3] net: macb: candidate fixes for silent TX stall on BCM2712/RP1:
- lore thread: https://lore.kernel.org/netdev/cover.1777064117.git.lukasz@raczylo.com/T/
- related issues: cilium/cilium#43198, Ubuntu launchpad #2133877
| Patch | What it does |
|---|---|
0001-net-macb-flush-PCIe-posted-write-after-TSTART-doorbell.patch |
Read-back of NCR after each TSTART write so the doorbell reaches the MAC before the function returns. |
0002-net-macb-re-check-ISR-after-IER-re-enable-in-macb_tx_poll.patch |
Reads ISR after IER re-enable in macb_tx_poll() — both a direct pending-TCOMP check and a PCIe read barrier for in-flight descriptor TX_USED DMA writes. |
0003-net-macb-add-TX-stall-watchdog-to-recover-from-lost-TCOMP.patch |
Per-queue delayed_work safety net. Calls the existing macb_tx_restart() if tx_tail hasn't advanced for ≥ 1 s while the ring is non-empty. |
vs. the version posted to netdev
The bodies of patches 1 and 2 are byte-identical between this directory and the netdev submission. Patch 3 has a 5-line variation in its macb.h hunk: this version is anchored against the raspberrypi/linux rpi-6.18.y vendor fork (which carries an extra bool tx_pending field on struct macb_queue); the netdev-submitted version is anchored against mainline (which doesn't). The semantic change — adding delayed_work tx_stall_watchdog_work and unsigned int tx_stall_last_tail to struct macb_queue — is the same in both.
License
The patches are derived works of the Linux kernel and inherit its license: GPL-2.0-only. This is consistent with the upstream Linux kernel and supersedes the MIT license that covers the rest of this build harness.
Author
Lukasz Raczylo lukasz@raczylo.com.
Adding more patches
Just drop a *.patch file in this directory. patches-linux copies anything matching *.patch into the kernel build's patch dir, and the build script applies them in sorted order. Use git format-patch style or plain unified diffs — both work.
For patches that need to apply against the vendor fork specifically, anchor them on what's there (e.g. the extra bool tx_pending field). For patches that should also be acceptable upstream, keep the diff minimal and avoid vendor-only context.