docs: the firmware is downloadable — WOA-Project reference drivers

The blobs turned out to be a public download rather than something to recover
from a lost backup. WOA-Project/Qualcomm-Reference-Drivers collects the
Windows-on-ARM driver cabinets by SoC, and three of them cover this machine
completely: qcdx850.cab has the zap shader and venus, qcipa850.cab has
ipa_fws.elf, and qcsubsys850.cab has the four DSP images plus WLANMDSP.MBN —
the WiFi firmware, which is not in the device tree's firmware-name list at all
and so was never on our list of things to look for.

Correct three claims elsewhere in the file that this disproves. `file` reports
these as ELF QUALCOMM DSP6 images, not as `data` — worth stating precisely,
since it is the quickest way to tell a real blob from a download that returned
an HTML error page. The sizes span 14KB to 60MB rather than "a few hundred KB
to a few MB". And the heading claiming they must come off the Windows partition
is no longer true of the easiest route.

Also narrow what c630-firmware puts in the initramfs. It globbed every .mbn in
the firmware directory, which would have pulled in the 60MB qcdsp2850.mbn and
inflated the initramfs roughly twentyfold. Only the GPU needs to be there —
msm_dpu probes at six seconds, while the initramfs is still root; the ADSP,
CDSP, SLPI, venus and modem all probe around forty seconds in and load from the
real root perfectly happily.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XWRjNJMistCy6ngXH5aJLS

overlay/usr/local/sbin/c630-firmware

@@ -34,14 +34,19 @@ fi
 qcom-firmware-extract "$@"
 
 echo
-# The ADSP has to be up before the root filesystem is mounted, so these have to
-# travel in the initramfs. Only write the glob now that the files exist —
-# dracut objects to install_items that match nothing.
+# Only the GPU zap shader has to travel in the initramfs. msm_dpu probes around
+# six seconds in, while the initramfs is still the root filesystem, and never
+# retries. Everything else — ADSP, CDSP, SLPI, venus, modem — is probed well
+# after the real root is mounted and loads from there quite happily.
+#
+# This matters: qcdsp2850.mbn alone is 60MB. Globbing the whole directory into
+# the initramfs, which is what this used to do, would have bloated it roughly
+# twentyfold to no purpose.
 FW_DIR=/usr/lib/firmware/updates/qcom/sdm850/LENOVO/81JL
-if compgen -G "${FW_DIR}/*.mbn" >/dev/null || compgen -G "${FW_DIR}/*.elf" >/dev/null; then
-    printf 'install_items+=" %s/*.mbn %s/*.elf "\n' "$FW_DIR" "$FW_DIR" \
-        > /etc/dracut.conf.d/20-c630-extracted-firmware.conf
-    echo "Extracted firmware will be included in the initramfs."
+if [ -f "${FW_DIR}/qcdxkmsuc850.mbn" ]; then
+    printf 'install_items+=" %s/qcdxkmsuc850.mbn "\n' "$FW_DIR" \
+        > /etc/dracut.conf.d/20-c630-zap-shader.conf
+    echo "GPU zap shader will be included in the initramfs."
 fi
 
 echo "Regenerating the initramfs..."