linux-kernel - Re: parisc: adjust L1_CACHE_BYTES to 128 bytes on PA8800 and PA8900 CPUs

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Date:	Thu, 03 Sep 2015 11:23:55 +0200
From:	Andreas Ziegler <andreas.ziegler@....de>
To:	Helge Deller <deller@....de>
CC:	linux-parisc@...r.kernel.org,
	Valentin Rothberg <valentinrothberg@...il.com>,
	Paul Bolle <pebolle@...cali.nl>,
	linux-kernel <linux-kernel@...r.kernel.org>,
	John David Anglin <dave.anglin@...l.net>
Subject: Re: parisc: adjust L1_CACHE_BYTES to 128 bytes on PA8800 and PA8900
 CPUs

Hi Helge,

today's linux-next tree (next-20150903) contains commit 20f924902ff6
("parisc: adjust L1_CACHE_BYTES to 128 bytes on PA8800 and PA8900 CPUs")
which you authored.

I noticed it because we[0] are running a daily analysis on all commits
in linux-next as part of our research and our tools reported it.

In the patch, you create the following #if defined() structure in
arch/parisc/include/asm/cache.h (lines 16 and following):

 #if defined(CONFIG_PA8X00)
  ...
 #elif defined(CONFIG_PA20)
  ...
 #else
  ...
 #endif

In Kconfig, CONFIG_PA20 is defined as the following
(arch/parisc/Kconfig, line 163):

config PA20
  def_bool y
  depends on PA8X00

This means that CONFIG_PA20 can and will only be enabled if
CONFIG_PA8X00 has already been enabled, which means that the contents of
the "#elif defined(CONFIG_PA20)" block can never be reached: its
condition is only evaluated if CONFIG_PA8X00 is disabled, but then
CONFIG_PA20 can never be enabled either.

Best regards,

Andreas

[0] https://cados.cs.fau.de
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