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From:   Masahiro Yamada <yamada.masahiro@socionext.com>
Date:   Thu, 23 Aug 2018 16:20:40 +0900
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Subject: Re: please revert commit ce8556cca6 "kbuild: verify that $DEPMOD is
 installed" introduced in v4.18.4.
To:     Randy Dunlap <rdunlap@infradead.org>
Cc:     Dmitry Torokhov <dmitry.torokhov@gmail.com>,
        "Dr. H. Nikolaus Schaller" <hns@goldelico.com>,
        Lucas De Marchi <lucas.demarchi@profusion.mobi>,
        Lucas De Marchi <lucas.de.marchi@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Jessica Yu <jeyu@kernel.org>,
        Chih-Wei Huang <cwhuang@linux.org.tw>,
        "3.8+" <stable@vger.kernel.org>,
        lkml <linux-kernel@vger.kernel.org>,
        Discussions about the Letux Kernel 
        <letux-kernel@openphoenux.org>,
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2018-08-23 10:07 GMT+09:00 Randy Dunlap <rdunlap@infradead.org>:
> On 08/22/2018 05:39 PM, Dmitry Torokhov wrote:
>> On Wed, Aug 22, 2018 at 4:35 PM Randy Dunlap <rdunlap@infradead.org> wrote:
>>>
>>> On 08/22/2018 11:53 AM, H. Nikolaus Schaller wrote:
>>>> This patch requires that /sbin/depmod is installed and installable on
>>>> the build host.
>>>>
>>>> But not all build hosts for cross compiling Linux are Linux systems
>>>> and are able to provide a working port of depmod, especially at the
>>>> file patch /sbin/depmod.
>>>>
>>>> I use, for example, a Darwin system to cross compile Linux and I run
>>>> depmod -a on the embedded system once, after installing a new Linux
>>>> kernel there.
>>>>
>>>> I have no problem with seeing a warning, but aborting the build process
>>>> is IMHO a bad idea since the previous behaviour didn't harm many people
>>>> as far as I see. Probably 99% of people compiling Linux kernels do that
>>>> on Linux and 99% of those have depmod installed for optimal operation of
>>>> their build host. So IMHO printing the warning is good enough.
>>>
>>> Thanks for the report and sorry about the problem.
>>>
>>> I'm OK with changing the error to a warning.
>>> Does the patch below work for you?
>>
>> Why would one want a warning on a host that never runs "make modules_install"?
>> Can this check be only done when we actually try to install modules?
>
>
> So Nikolaus:  how do you provoke this problem that you are reporting?
> It's not just a theoretical problem, is it?
>
> The way that I read the top-level Makefile, this check for $DEPMOD only happens
> when you run "make modules_install".
>
> --
> ~Randy


Unless I am misunderstanding, he wants to use
"make modules_install" just for copying modules.

Then, he will run depmod on the target system later.


-- 
Best Regards
Masahiro Yamada