error: 'ARPHRD_MCTP' undeclared (first use in this function)

[cpackham-atlnz]

systemd version the issue has been seen with

v249
v243

Used distribution

custom build for embedded devices

Linux kernel version used (uname -a)

Tip of Linus's tree v5.14-10557-ga3fa7a101dcf

CPU architecture issue was seen on

aarch64

Expected behaviour you didn't see

Successful compilation

Unexpected behaviour you saw

Build fails with following message

armv8,systemd: FAILED: src/basic/libbasic.a.p/arphrd-list.c.o
armv8,systemd: aarch64-unknown-linux-gnu-gcc --sysroot=/usr/src/linuxbox/output/armv8/systemd/staging -Isrc/basic/libbasic.a.p -Isrc/basic -I../src/basic -Isrc/fundamental -I../src/fundamental -Isrc/systemd -I../src/systemd -I. -I.. -I/usr/src/linuxbox/output/armv8/syste
md/staging/usr/include -I/usr/src/linuxbox/output/armv8/systemd/staging/usr/include/libmount -I/usr/src/linuxbox/output/armv8/systemd/staging/usr/include/blkid -fdiagnostics-color=always -D_FILE_OFFSET_BITS=64 -Wall -Winvalid-pch -Wextra -std=gnu99 -g -Wno-format-signedn
ess -Wno-missing-field-initializers -Wno-unused-parameter -Wno-unused-result -Wdate-time -Wendif-labels -Werror=format=2 -Werror=implicit-function-declaration -Werror=incompatible-pointer-types -Werror=overflow -Werror=return-type -Werror=shift-count-overflow -Werror=shi
ft-overflow=2 -Werror=undef -Wfloat-equal -Wimplicit-fallthrough=5 -Winit-self -Wlogical-op -Wmissing-include-dirs -Wmissing-noreturn -Wnested-externs -Wold-style-definition -Wpointer-arith -Wredundant-decls -Wshadow -Wstrict-aliasing=2 -Wstrict-prototypes -Wsuggest-attr
ibute=noreturn -Wwrite-strings -Wno-maybe-uninitialized -Werror=missing-declarations -Werror=missing-prototypes -fdiagnostics-show-option -ffast-math -fno-common -fno-strict-aliasing -fstack-protector -fstack-protector-strong -fvisibility=hidden --param=ssp-buffer-size=4
 -Wno-shadow -include config.h -fPIC -pthread -fvisibility=default -MD -MQ src/basic/libbasic.a.p/arphrd-list.c.o -MF src/basic/libbasic.a.p/arphrd-list.c.o.d -o src/basic/libbasic.a.p/arphrd-list.c.o -c ../src/basic/arphrd-list.c
armv8,systemd: In file included from ../src/basic/arphrd-list.c:12:
armv8,systemd: src/basic/arphrd-from-name.gperf: In function 'lookup_arphrd':   
armv8,systemd: src/basic/arphrd-from-name.gperf:62:16: error: 'ARPHRD_MCTP' undeclared (first use in this function); did you mean 'ARPHRD_FCPP'?
armv8,systemd:  MCTP, ARPHRD_MCTP
armv8,systemd:                 ^~
armv8,systemd:                 ARPHRD_FCPP
armv8,systemd: src/basic/arphrd-from-name.gperf:62:16: note: each undeclared identifier is reported only once for each function it appears in
armv8,systemd: In file included from ../src/basic/arphrd-list.c:13:
armv8,systemd: src/basic/arphrd-to-name.h: In function 'arphrd_to_name':
armv8,systemd: src/basic/arphrd-to-name.h:55:14: error: 'ARPHRD_MCTP' undeclared (first use in this function); did you mean 'ARPHRD_FCPP'?
armv8,systemd:          case ARPHRD_MCTP: return "MCTP";
armv8,systemd:               ^~~~~~~~~~~
armv8,systemd:               ARPHRD_FCPP

I'm assuming there's some change in the definition of ARPHRD_MCTP in the kernel uapi headers. I haven't investigated that yet.

Steps to reproduce the problem

Unsure, might be possible to reproduce with the right packages under buildroot

Additional program output to the terminal or log subsystem illustrating the issue

[cpackham-atlnz]

Looks like there's a bundled src/basic/linux/if_arp.h which doesn't have the ARPHRD_MCTP definition. Looking at the build line above -Isrc/basic -I../src/basic is before the "normal" -I/usr/src/linuxbox/output/armv8/systemd/staging/usr/include where the header from the kernel is placed.