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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat, 2 Jan 2021 16:51:03 +0900
Message-ID: <CAK7LNASQZ7SWrAykdH71iq6SyLj=gG-EGhCy8SHkDz_bdq2BMw@mail.gmail.com>
Subject: Re: Linux 5.11-rc1
To:     Sedat Dilek <sedat.dilek@gmail.com>
Cc:     Pavel Machek <pavel@ucw.cz>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
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On Sat, Jan 2, 2021 at 3:55 AM Sedat Dilek <sedat.dilek@gmail.com> wrote:
>
> On Fri, Jan 1, 2021 at 5:14 PM Pavel Machek <pavel@ucw.cz> wrote:
> >
> > Hi!
> > > >
> > > > > $ dpkg -L kmod | grep bin | grep depmod
> > > > > /sbin/depmod
> > > > >
> > > > > $ which depmod
> > > > > [ empty ]
> > > > >
> > > > > $ echo $PATH
> > > > > /opt/proxychains-ng/bin:/home/dileks/bin:/usr/local/bin:/usr/bin:/bin:/usr/local/games:/usr/games
> > >
> > > Ok, I think this is a broken setup that has a separate /sbin but does
> > > not have it in the PATH.
> >
> > That's how it is supposed to work, AFAICT. It is so on Debian here,
> > for example.
> >
> > /sbin is for management commands, why would I have it in PATH when
> > running as normal user?
> >
>
> I am here on Debian/testing AMD64 and waiting for feedback [2].
>
> For now I have applied the diff from [1].
>
> - Sedat -
>
> [1] https://marc.info/?l=linux-kbuild&m=160919738006768&w=2
> [2] https://marc.info/?l=linux-kernel&m=160919729606750&w=2


PATH for the root on Debian is
/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin


depmod is used from 'make module_install'.

For the native module installation to the host machine,
module_install is run after 'su -'
or 'sudo', which successfully finds depmod in /sbin.


I also tested 'make deb-pkg' with/without
rootless builds. It also successfully found depmod
in /sbin, presumably dpkg tools automatically tweak
PATH env variable.


Maybe, the problem is when we run 'make modules_install'
for cross compilation, which we do not necessarily
require the root permission.

Users can still adjust PATH in ~/.profile, but
somebody may think breaking the legacy behavior
is annoying.

So, after some consideration, the workaround by Linus
looks good to me.


--
Best Regards
Masahiro Yamada