On Thu, Nov 8, 2018 at 8:27 PM Mikolaj Ch <mikich7777@xxxxxxxxx> wrote:
>
> Hi,
>
> I noticed a problem while installing external module with command:
> make M=dir modules_install
>
> For me it appeared in two separate cases:
> - when 'dir' includes symbolic link
> - when 'dir' includes double slash.
>
> For this two cases module is installed to:
> lib/modules/<kernel_version>/extra/<'dir>'/<module_name>.ko
> instead of
> lib/modules/<kernel_version/extra/<module_name>.ko
>
> I've traced the problem and it appeared to be in:
> scripts/Makefile.modinst in line:
>
> in line 12 the path to module is taken from MODVERDIR/*.mod file:
> __modules := $(sort $(shell grep -h '\.ko$$' /dev/null $(wildcard
> $(MODVERDIR)/*.mod)))
>
> and then directory part of this path is going to be removed with subst
> function in line 30:
> ext-mod-dir = $(INSTALL_MOD_DIR)$(subst $(patsubst
> %/,%,$(KBUILD_EXTMOD)),,$(@D))
>
> but it fails since KBUILD_EXTMOD is not evaluated path (can include
> symlink or double slash) and @D is direct/evaluated path from *.mod
> file.
> -------------------------
> the same in more details:
> -------------------------
>
> In kernel Makefile the following variables are set:
> KBUILD_EXTMOD = $M
> MODVERDIR = $KBUILD_EXTMOD/.tmp_versions
>
>
> in scripts/Makefile.modinst in lines:
> __modules := $(sort $(shell grep -h '\.ko$$' /dev/null $(wildcard
> $(MODVERDIR)/*.mod)))
> modules := $(patsubst %.o,%.ko,$(wildcard $(__modules:.ko=.o)))
>
> The path in $MODVERDIR is evaluated correctly by shell (symbolic link
> is followed and double slash is interpreted as single slash)
> and the path to the module $modules is taken form $(MODVERDIR)/*.mod file).
I tested it, but it did not happen to me.
The path in $(MODVERDIR) reflects
the directory path given via M= option for 'make modules'.
I guess you passed a normalized path to
'make M=<dir> modules'
then, a non-normalized path to
'make M=<dir> modules_install'
Didn't you ?
> The $modules is then passed to __modinst function as $@ where in line:
> ext-mod-dir = $(INSTALL_MOD_DIR)$(subst $(patsubst
> %/,%,$(KBUILD_EXTMOD)),,$(@D))
>
> subst function substitutes text from $KBUILD_EXTMOD to empty string in
> directory part of $@ (@D) but here KBUILD_EXTMOD is different then @D.
>
>
> Can't directory part be remove differently if using absolute paths to
> avoid such problems ?
I think this is a hypothetical problem, like
What if a user passed different passes for
'make modules' and 'make modules_install' ?
$ make -C <path_to_kernel_src> M=$PWD
is the idiom to build external modules.
M=$PWD will do a good job for you.
See Documentation/kbuild/modules.txt
> Regards,
> Mikolaj Chadzynski
--
Best Regards
Masahiro Yamada
