linux-kernel - Re: [PATCH 2/8] um: Do not use SUBARCH

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Date:	Thu, 26 Sep 2013 17:13:46 +0530
From:	Ramkumar Ramachandra <artagnon@...il.com>
To:	Richard Weinberger <richard@....at>
Cc:	linux-arch@...r.kernel.org, Michal Marek <mmarek@...e.cz>,
	geert@...ux-m68k.org, ralf@...ux-mips.org, lethal@...ux-sh.org,
	Jeff Dike <jdike@...toit.com>,
	Guan Xuetao <gxt@...c.pku.edu.cn>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	linux-kbuild@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
	linux-m68k@...ts.linux-m68k.org, linux-mips@...ux-mips.org,
	linux-sh@...r.kernel.org,
	user-mode-linux-devel@...ts.sourceforge.net
Subject: Re: [PATCH 2/8] um: Do not use SUBARCH

Richard Weinberger wrote:
>> Auto-detection of SUBARCH, which can be done with a simple call to
>> uname -m (the 90% case). The second patch I submitted prevented
>> spawning xterms unnecessarily, which we discussed was a good move.
>
> Covering only 90% of all cases is not enough.
> We must not break existing setups.
> That's also why my "Get rid of SUBARCH" series is not upstream.

Mine covers 100% of the cases. My series is about auto-detection of
SUBARCH, not its removal: you can still set a SUBARCH from the
command-line; existing setups don't break.

> Your second patch changed CONFIG_CON_CHAN to pts, which is ok but not
> a major issue.

"Major" or "minor" is purely your classification: don't impose your
value judgement on reasonable patches. I am the user, and I demand a
pleasant build process and ui. Moreover, how do you expect more
contributions to come in until existing patches make it to upstream?

> The xterms are also not spawning unnecessarily they spawn upon a tty device is opened.
> With your patch UML create another pts. Thus, the spawning is hidden...

It connects to an existing host pts device instead of spawning a new
xterm and connecting to the console io on that. Why is that not
desirable?

> I did not push it upstream because it depended on your first one and as I said, it's not critical.
> This does not mean that I moved it to /dev/null.

... and you still haven't told me what's wrong with my first patch.

> Again, the plan is to get rid of SUBARCH at all.

You've been harping about this plan for the last N months, and nothing
has happened so far. It's time to stop planning, and accept good work.

>>> make defconfig ARCH=um SUBARCH=x86 (or SUBARCH=i386) will create a defconfig for 32bit.
>>> make defconfig ARCH=um SUBARCH=x86_64 one for 64bit.
>>
>> Yes, that's how I prepared the patch in the first place.
>
> So, nothing is broken.

So the user is Ugly and Stupid for expecting:

  $ make defconfig ARCH=um
  $ make -j 8 ARCH=um

to work? Stop denying problems, no matter how "major" or "minor" they are.

> If you want "make defconfig ARCH=um" creating a defconfig for the correct arch you need
> more than your first patch.

No, you don't. Try it for yourself and see. Set a SUBARCH if you like,
and it'll still work fine.

> Again, "Get rid of SUBARCH" series has the same goal.

For the last time, getting rid of SUBARCH is Wrong and Undesirable.

-- 8< --
Here's a transcript spoonfeeding you the impact of my first patch:

  $ make defconfig ARCH=um SUBARCH=i386
  *** Default configuration is based on 'i386_defconfig'
  #
  # configuration written to .config
  #
  $ make defconfig ARCH=um SUBARCH=x86_64
  *** Default configuration is based on 'x86_64_defconfig'
  #
  # configuration written to .config
  #
  $ make defconfig ARCH=um
  *** Default configuration is based on 'x86_64_defconfig'
  #
  # configuration written to .config
  #

In the last case, notice how defconfig automatically picks up
x86_64_defconfig correctly: if I were on an i386 machine, it would
have picked up i386_defconfig like in the first case. Without my
patch, the last case would have incorrectly picked up an i386
defconfig, which is Stupid and Wrong.
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