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raspberrypi
Undefined symbol failures if `CONFIG_USB=m`
Describe the bug
If CONFIG_USB_DWCOTG=y is set but CONFIG_USB=m, building the 6.1.73/stable_20240124 (and likely previous) kernel(s) fails with:
LD .tmp_vmlinux.kallsyms1
ld.lld: error: undefined symbol: usb_hcd_check_unlink_urb
>>> referenced by xarray.c
>>> vmlinux.o:(_complete)
>>> referenced by xarray.c
>>> vmlinux.o:(dwc_otg_urb_dequeue)
ld.lld: error: undefined symbol: usb_hcd_unlink_urb_from_ep
>>> referenced by xarray.c
>>> vmlinux.o:(_complete)
>>> referenced by xarray.c
>>> vmlinux.o:(_complete)
>>> referenced by xarray.c
>>> vmlinux.o:(dwc_otg_urb_enqueue)
>>> referenced 1 more times
ld.lld: error: undefined symbol: usb_hcd_giveback_urb
>>> referenced by xarray.c
>>> vmlinux.o:(_complete)
>>> referenced by xarray.c
>>> vmlinux.o:(completion_tasklet_func)
>>> referenced by xarray.c
>>> vmlinux.o:(dwc_otg_urb_dequeue)
ld.lld: error: undefined symbol: usb_create_hcd
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_init)
ld.lld: error: undefined symbol: usb_put_hcd
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_init)
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_remove)
ld.lld: error: undefined symbol: usb_add_hcd
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_init)
ld.lld: error: undefined symbol: usb_remove_hcd
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_remove)
ld.lld: error: undefined symbol: usb_hcd_resume_root_hub
>>> referenced by xarray.c
>>> vmlinux.o:(hcd_start)
>>> referenced by xarray.c
>>> vmlinux.o:(_start)
ld.lld: error: undefined symbol: usb_hcd_link_urb_to_ep
>>> referenced by xarray.c
>>> vmlinux.o:(dwc_otg_urb_enqueue)
make[3]: *** [/usr/src/linux-6.1.73-raspberrypi/scripts/Makefile.vmlinux:34: vmlinux] Error 1
make[2]: *** [/usr/src/linux-6.1.73-raspberrypi/Makefile:1255: vmlinux] Error 2
make[1]: *** [/usr/src/linux-6.1.73-raspberrypi/Makefile:369: __build_one_by_one] Error 2
make: *** [Makefile:238: __sub-make] Error 2
Steps to reproduce the behaviour
cd linux ; make USB_DWCOTG=y USB=m clean vmlinux
Device (s)
Raspberry Pi CM4
System
Kernel 6.1.73
Logs
No response
Additional context
The easy fix would be to make CONFIG_USB_DWCOTG depend on CONFIG_USB=y, but might it be possible to fix the DWC driver code to be able to be built as a module itself, or integrated in such a way that it works if USB support overall is a module?
Similarly, with 6.6.20/ 6f16847710cc0502450788b9f12f0a14d3429668 (untagged but matching https://github.com/raspberrypi/firmware/tree/1.20240306), CONFIG_FB_BCM2708 requires CONFIG_FB_DEVICE (for dev in struct fb_info), despite the Help text for CONFIG_FB_DEVICE reading:
Say Y here if you want the legacy /dev/fb* device file and interfaces within sysfs anc [sic] procfs. It is only required if you have userspace programs that depend on fbdev for graphics output. This does not affect the framebuffer console. If unsure, say N.
Why are you singling out 6.1 for the USB_DWCOTG dependency problem? For me, the 6.6 kernel is the same.
See #6112. Note that this fixes the rpi-6.6.y tree. rpi-6.1.y is not being developed on, but these patches could be back-ported as being low risk.
Why are you singling out 6.1 for the USB_DWCOTG dependency problem? For me, the 6.6 kernel is the same.
I've not tested USB_DWCOTG on 6.6 myself, but I'm not meaning to infer the the issue is specific to 6.1.
(When I first filed the bug, I was trying to build a 6.1 kernel. The 6.6 kernel sources still aren't tagged by the looks of things (see https://github.com/raspberrypi/linux/issues/6063), but I've moved on to using them regardless.)