After the configuration descriptor's first 9 bytes the event loop asked for
min(wTotalLength, 128) whatever it was. A wTotalLength of 9 or less was then
asked for again as "short" -- for ever, that slot never leaving enumeration
(#170); 0 also issued a zero-length data stage. A set longer than the 128-byte
buffer was cut without a word, its later interfaces never seen (#171).
The decision is usb_config_request_length() (moved out of the event loop,
then fixed): 9 or less is 0 -- "xhci: a configuration of N bytes has no
interface -- not used", and nothing more is asked; longer than the buffer is
cut and said -- "xhci: config of N bytes cut to 128 -- rest unseen" (at most
53 characters). The buffer stays 128 bytes; its size is #171's to rule.
kernel/tests/test_usb_config.c, seen to fail first against the decision as it
was (10 failures: wTotalLength 1 to 9 asked for again, the cut unsaid), now
20 checks, 0 failures. Both runs in logs/20261112-180140/kernel-tests/. Built for amd64,
aarch64 and riscv64; the boots come with the protocol. #171's other box, a
composite device on the SER5, is Captain Bob's.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017RzZgrf7V7Zk2iczBXDRbm
xhci.c's XHCI_XFER_CONFIG_DESC_FULL case walked the descriptor set inline, in
the event loop, where nothing could test it. The walk is now
usb_config_parse() (kernel/src/usb/usb_config.c), returning what it found;
the case acts on it as before -- the same messages, the same decisions: the
first Interface descriptor only, a BOT interface's bulk endpoints (the last of
each direction), a boot keyboard's first interrupt IN endpoint, bLength 0
ending the walk, nothing read past len. One difference, in debug output only:
the bulk endpoints are logged IN then OUT, not in descriptor order.
kernel/tests/test_usb_config.c, 7 checks, pins the walk as moved: a BOT stick
as QEMU presents it, a boot keyboard with its HID descriptor, a mouse before a
drive (the first interface only), a drive with bulk IN only, bLength 0, an
endpoint cut by len, an interface cut before its protocol byte. All pass.
Built for amd64, aarch64, riscv64; the boots come with the protocol (a data
stick enumerates through this path). The fixes for #170 and #171 follow.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017RzZgrf7V7Zk2iczBXDRbm
Claude