linux-kernel - Re: [PATCH v2] early_printk: consolidate random copies of identical code

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Date:	Thu, 7 Mar 2013 15:20:26 -0500
From:	Paul Gortmaker <paul.gortmaker@...driver.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
CC:	Mike Frysinger <vapier@...too.org>, Ingo Molnar <mingo@...nel.org>,
	Randy Dunlap <rdunlap@...radead.org>,
	<linux-kernel@...r.kernel.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Russell King <linux@....linux.org.uk>,
	Michal Simek <monstr@...str.eu>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mundt <lethal@...ux-sh.org>,
	"David S. Miller" <davem@...emloft.net>,
	Chris Metcalf <cmetcalf@...era.com>,
	Richard Weinberger <richard@....at>
Subject: Re: [PATCH v2] early_printk: consolidate random copies of identical
 code

On 13-03-07 02:25 PM, Andrew Morton wrote:
> On Thu, 7 Mar 2013 14:15:54 -0500 Paul Gortmaker <paul.gortmaker@...driver.com> wrote:
> 
>> [v2: essentially unchanged since v1, so I've left the acked/reviewed
>>  tags.  There was a compile fail[1] for a randconfig with EARLY_PRINTK=y
>>  and PRINTK=n, because the early_console struct and early_printk calls
>>  were nested within an #ifdef CONFIG_PRINTK -- moving that whole block
>>  exactly as-is to be outside the #ifdef CONFIG_PRINTK fixes the randconfig
>>  and still works for everyday sane configs too.]
>>  [1] http://marc.info/?l=linux-next&m=136219350914998&w=2   
> 
> You did this:
> 

[...]

> _
> 
> Problem is, that won't fix the various compilation problems we've had. 
> See yesterday's lkml thread "linux-next: build failure after merge of
> the final tree (akpm tree related)"

Unless I'm missing something, the easy fix for that is to just
unconditionally have an early_console, i.e. this one line change
on top of the v2 patch:

diff --git a/kernel/printk.c b/kernel/printk.c
index 7664e49..86799bf 100644
--- a/kernel/printk.c
+++ b/kernel/printk.c
@@ -120,6 +120,7 @@ struct console_cmdline
 static struct console_cmdline console_cmdline[MAX_CMDLINECONSOLES];
 static int selected_console = -1;
 static int preferred_console = -1;
+struct console *early_console;
 int console_set_on_cmdline;
 EXPORT_SYMBOL(console_set_on_cmdline);
 
@@ -1718,7 +1719,6 @@ static size_t cont_print_text(char *text, size_t size) { return 0; }
 #endif /* CONFIG_PRINTK */
 
 #ifdef CONFIG_EARLY_PRINTK
-struct console *early_console;
 
 void early_vprintk(const char *fmt, va_list ap)
 {


Then you don't have to spray any of those ifdefs into the sparc code.
I've build tested the above tweak for sparc32/64 defconfig.  Also built
for powerpc (sbc8548) -- note that you can't turn off EARLY_PRINTK
for ppc as it is:

config EARLY_PRINTK
        bool
        default y

i.e. no help text and no prompting. And the kooky randconfig and a
sane x86 defconfig are still OK too.  Unless you see something else
that I'm overlooking, I can send a v3 that incorporates the above
small tweak.

Thanks,
Paul.
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