linux-kernel - Re: rfc: remove early_printk from a few arches? (blackfin, m68k, mips)

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Message-ID: <yw1xy4q4exo9.fsf@unicorn.mansr.com>
Date:	Fri, 19 Dec 2014 10:33:42 +0000
From:	Måns Rullgård <mans@...sr.com>
To:	Joe Perches <joe@...ches.com>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	linux-arch <linux-arch@...r.kernel.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Geert Uytterhoeven <geert@...ux-m68k.org>,
	linux-m68k <linux-m68k@...ts.linux-m68k.org>,
	Steven Miao <realmz6@...il.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	linux-mips <linux-mips@...ux-mips.org>
Subject: Re: rfc: remove early_printk from a few arches? (blackfin, m68k, mips)

Joe Perches <joe@...ches.com> writes:

> On Fri, 2014-12-19 at 01:43 +0000, Måns Rullgård wrote:
>> What exactly are you proposing to remove?
>
> Optionally compile out
> kernel/printk/printk.c:early_printk()
> even if CONFIG_EARLY_PRINTK is enabled.
>
>> I see no unused code related
>> to early printk (in any variant) under arch/mips.
>
> I think there could be yet another CONFIG option
> to specifically enable the early_printk function
> for the arches that use it.

Why bother?  On MIPS it would save 132 bytes of compiled code.

> The kernel/printk/early_printk() function seems
> used only by arm/microblaze/tile/x86.

Rather than introduce more config complexity, you could try to remove
the 7 remaining uses of early_printk().

- arch/arm/mach-socfpga
  Single early_printk("Early printk initialized\n") call serving no
  apparent purpose can probably be safely deleted.  Since there are no
  other early_printk() calls, this information seems rather useless.

- arch/microblaze, arch/tile, arch/x86
  These all do a register_console() for the early console, so regular
  printk() should work.  Moreover, x86 allows multiple early consoles,
  but calling early_printk() will only output to the last one specified.

-- 
Måns Rullgård
mans@...sr.com
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