[DRBD-user] Compilation errors on Rockchip for DRBD v9

[Günther Berger]

Dear users of the mailing list,

I've got compilation errors for the recent version of DRBD v9 on my Tinkerboard:
---
make[1]: Entering directory '/usr/src/drbd/drbd'

   Calling toplevel makefile of kernel source tree, which I believe is in
   KDIR=/lib/modules/5.10.6-rockchip/build

make -C /lib/modules/5.10.6-rockchip/build   M=/usr/src/drbd/drbd  modules
 GENPATCHNAMES   5.10.6-rockchip
 SPATCH   6acef4b9ff4352c590dc4ea075ca20d0  5.10.6-rockchip
 PATCH
patching file drbd-headers/linux/genl_magic_struct.h
patching file drbd_receiver.c
patching file drbd_main.c
patching file drbd_nl.c
patching file drbd_debugfs.c
patching file drbd-headers/linux/genl_magic_func.h
 CC [M]  /usr/src/drbd/drbd/drbd_debugfs.o
 CC [M]  /usr/src/drbd/drbd/drbd_bitmap.o
 CC [M]  /usr/src/drbd/drbd/drbd_proc.o
 CC [M]  /usr/src/drbd/drbd/drbd_sender.o
 CC [M]  /usr/src/drbd/drbd/drbd_receiver.o
 CC [M]  /usr/src/drbd/drbd/drbd_req.o
 CC [M]  /usr/src/drbd/drbd/drbd_actlog.o
 CC [M]  /usr/src/drbd/drbd/lru_cache.o
CC [M]  /usr/src/drbd/drbd/drbd_main.o
 CC [M]  /usr/src/drbd/drbd/drbd_strings.o
 CC [M]  /usr/src/drbd/drbd/drbd_nl.o
 CC [M]  /usr/src/drbd/drbd/drbd_interval.o
 CC [M]  /usr/src/drbd/drbd/drbd_state.o
 CC [M]  /usr/src/drbd/drbd/drbd-kernel-compat/drbd_wrappers.o
 CC [M]  /usr/src/drbd/drbd/drbd_nla.o
 CC [M]  /usr/src/drbd/drbd/drbd_transport.o
 GEN     /usr/src/drbd/drbd/drbd_buildtag.c
 CC [M]  /usr/src/drbd/drbd/drbd_buildtag.o
 LD [M]  /usr/src/drbd/drbd/drbd.o
 CC [M]  /usr/src/drbd/drbd/drbd_transport_tcp.o
 MODPOST /usr/src/drbd/drbd/Module.symvers
ERROR: modpost: "__aeabi_ldivmod" [/usr/src/drbd/drbd/drbd.ko] undefined!
ERROR: modpost: "__aeabi_uldivmod" [/usr/src/drbd/drbd/drbd.ko] undefined!
make[3]: *** [scripts/Makefile.modpost:111:
/usr/src/drbd/drbd/Module.symvers] Error 1
make[3]: *** Deleting file '/usr/src/drbd/drbd/Module.symvers'
make[2]: *** [Makefile:1709: modules] Error 2
make[1]: *** [Makefile:132: kbuild] Error 2
make[1]: Leaving directory '/usr/src/drbd/drbd'
make: *** [Makefile:131: module] Error 2
---

The architecture of the Tinkerboard is "armv7l" which is 32 bit. The
error lines with "modpost" indicate that in the source code of DRBD
uses some 64 bit division that the used Linux kernel does not
support.I also tried the compilation on my Odroid C2 having a 64
architecure with success. I also tried other Linux kernel version,
e.g. 4.x, 5.2.x and 5.8.x.

I hope someone is able to help me,

Günther