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Shen MintaoandClaude Opus 5.5 c97644a43a docs: document OpenWrt cfg80211 backport builds
27af5ad added the CFG80211_VERSION make variable for OpenWrt builds that
use a newer mac80211 backport than the target kernel, but it is only
described in a Makefile comment. Document how to pass it from an OpenWrt
package Makefile, link the notes from the installation steps, and add
the build script and the kernel/backports combinations verified for
issue #94.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
2026-09-24 14:59:37 +08:00

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# OpenWrt backports build regression
This checks complete module compilation and MODPOST against real kernel and
wireless-stack headers. It requires an already prepared SDK/buildroot with
cfg80211/mac80211 headers and `mac80211.symvers` staged. It does not install
packages or load modules.
For the x86_64 SDK used in issue #94:
```sh
sdk=/path/to/openwrt-sdk
kernel="$sdk/build_dir/target-x86_64_musl/linux-x86_64/linux-6.12.94"
export STAGING_DIR="$sdk/staging_dir/target-x86_64_musl"
export PATH="$sdk/staging_dir/toolchain-x86_64_gcc-14.3.0_musl/bin:$PATH"
bash tests/openwrt-backports/build.sh \
"$kernel" "$STAGING_DIR/usr/include" \
"$kernel/../symvers/mac80211.symvers" 6.18.26 \
ARCH=x86_64 CROSS_COMPILE=x86_64-openwrt-linux-musl-
```
The script copies the current driver into a fresh temporary directory and
checks that all three `.ko` files are produced. Additional make arguments
can select a compiler or architecture. Use matching headers, configuration
and symbol versions throughout; changing only the version argument is not
a substitute for the matching wireless stack.
## Verified on 2026-09-17
- OpenWrt 25.12.5 x86_64 SDK: Linux 6.12.94, GCC 14.3.0, backports 6.18.26
with the mac80211 patches from OpenWrt revision `f5dae5ece4` applied:
all three modules compile and pass MODPOST with the kernel's `-Werror`.
- Original driver revision `9594c5c`, on the same kernel/backports combination:
reproduces both RX argument-count errors and the four incompatible
`set_monitor_channel`, `set_wiphy_params`, `set_tx_power`, `get_tx_power`
callbacks. This comparison uses `-Wno-error=unused-label`, as the issue's
log does, to reach those failures. The fixed build needs no such override.
- Native kernel headers 6.11.0-17, 6.17.0-14 and 7.2.0-070200, with
`CFG80211_VERSION` unset: all three modules compile and pass MODPOST.
The 7.2 check uses GCC 14 and reports compiler/attribute warnings because
those headers were built with GCC 15.
These are build checks. They do not validate an installable OpenWrt package,
firmware loading, Wi-Fi connectivity or Bluetooth operation on hardware.