Re: single target builds are broken

From: Joe Perches <joe@perches.com>
To: Masahiro Yamada <masahiroy@kernel.org>,
	Vegard Nossum <vegard.nossum@oracle.com>
Cc: Jens Axboe <axboe@kernel.dk>, LKML <linux-kernel@vger.kernel.org>,
	Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>
Subject: Re: single target builds are broken
Date: Tue, 31 Mar 2020 10:56:20 -0700	[thread overview]
Message-ID: <78a8ba04459f8a4ea6bcb8811f35490018b763f2.camel@perches.com> (raw)
In-Reply-To: <CAK7LNAT-8TbLRPB=PNsbAORKYvYL+m3JmA-iSDieK8Uv7MAvGA@mail.gmail.com>

On Wed, 2020-04-01 at 01:03 +0900, Masahiro Yamada wrote:
> On Tue, Mar 31, 2020 at 8:02 PM Vegard Nossum <vegard.nossum@oracle.com> wrote:
> > It's really useful to be able to build object files separately, but as
> > if it was part of the kernel (so e.g. with all the gcc flags, include
> > paths, etc.).
[]
> So, there were lots of cases where single builds did not work:
> 
> https://www.spinics.net/lists/linux-kbuild/msg21921.html
> 
> The way to do this correctly is to
> descend directories one by one, parsing Makefiles.
> 
> With no entry in obj-y/m,
> Kbuild cannot determine where to build that object.
> 
> > At the very least, can we find a way to reduce the typing overhead for
> > testing one-offs like that? 'make STANDALONE=1 test.o' or something?
> 
> Probably, I do not want to do this.
> 
> Supporting everybody's demand is not a good idea.
> So, I draw a line somewhere.
> 
> Saving some typing is less important.

I too find this regression less than desirable.

make <single_object> is/was quite useful even
if it didn't always work.