On Fri, Oct 30, 2020 at 2:35 AM Anatol Pomozov <anatol.pomozov@xxxxxxxxx> wrote: > > Hi folks > > Here is a follow-up for this issue > https://github.com/Open-CAS/open-cas-linux/issues/540 > > opencas project builds an out-of-tree kernel module and uses > system-level kernel header. In my case these headers are installed to > /lib/modules/5.9.1-arch1-1/build > > So if I do > > $ cd /lib/modules/5.9.1-arch1-1/build > $ make kernelversion > > I get following output: > > mkdir: cannot create directory ‘.tmp_86541’: Permission denied > mkdir: cannot create directory ‘.tmp_86543’: Permission denied > mkdir: cannot create directory ‘.tmp_86545’: Permission denied > mkdir: cannot create directory ‘.tmp_86547’: Permission denied > ....... > mkdir: cannot create directory ‘.tmp_86626’: Permission denied > mkdir: cannot create directory ‘.tmp_86628’: Permission denied > mkdir: cannot create directory ‘.tmp_86630’: Permission denied > 5.9.1-arch1 This is because you did not pass M= option. /lib/modules/$(uname -r)/build is used for building external modules. You cannot work in that directory since it is usually read-only. You need to pass M=<path-to-your-module> This may work for you. $ cd /lib/modules/$(uname -r)/build $ mkdir $HOME/foo $ make M=$HOME/foo kernelversion > > Quick debugging shows that it comes from scripts/Kbuild.include > following lines in particular: > > # output directory for tests below > TMPOUT = $(if $(KBUILD_EXTMOD),$(firstword $(KBUILD_EXTMOD))/).tmp_$$$$ > > # try-run > # Usage: option = $(call try-run, $(CC)...-o "$$TMP",option-ok,otherwise) > # Exit code chooses option. "$$TMP" serves as a temporary file and is > # automatically cleaned up. > try-run = $(shell set -e; \ > TMP=$(TMPOUT)/tmp; \ > TMPO=$(TMPOUT)/tmp.o; \ > mkdir -p $(TMPOUT); \ > trap "rm -rf $(TMPOUT)" EXIT; \ > if ($(1)) >/dev/null 2>&1; \ > then echo "$(2)"; \ > else echo "$(3)"; \ > fi) > > > > TMPOUT points to headers directory and in my case it is a part of /usr > partition that restricts user writes. > > > TMPOUT should avoid writing to headers dir and use `mktemp` instead. -- Best Regards Masahiro Yamada
