linux-kernel - Re: [PATCH 1/2] Add /sys/firmware/memmap

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Message-ID: <20080626104524.2d7ed1ab@halley.suse.de>
Date:	Thu, 26 Jun 2008 10:45:24 +0200
From:	Bernhard Walle <bwalle@...e.de>
To:	Mikael Pettersson <mikpe@...uu.se>
Cc:	Vivek Goyal <vgoyal@...hat.com>, x86@...nel.org,
	linux-kernel@...r.kernel.org, kexec@...ts.infradead.org,
	yhlu.kernel@...il.com
Subject: Re: [PATCH 1/2] Add /sys/firmware/memmap

* Mikael Pettersson [2008-06-26 10:13]:
>
> Vivek Goyal writes:
>  > On Wed, Jun 25, 2008 at 09:57:05PM +0200, Bernhard Walle wrote:
>  > > This patch adds /sys/firmware/memmap interface that represents the BIOS
>  > > (or Firmware) provided memory map. The tree looks like:
>  > > 
>  > >     /sys/firmware/memmap/0/start   (hex number)
>  > >                            end     (hex number)
>  > >                            type    (string)
>  > >     ...                 /1/start
>  > >                            end
>  > >                            type
>  > > 
>  > > With the following shell snippet one can print the memory map in the same form
>  > > the kernel prints itself when booting on x86 (the E820 map).
>  > > 
>  > >   --------- 8< --------------------------
>  > >     #!/bin/sh
>  > >     cd /sys/firmware/memmap
>  > >     for dir in * ; do
>  > >         start=$(cat $dir/start)
>  > >         end=$(cat $dir/end)
>  > >         type=$(cat $dir/type)
>  > >         printf "%016x-%016x (%s)\n" $start $[ $end +1] "$type"
>  > >     done
>  > >   --------- >8 --------------------------
>  > > 
>  > > That patch only provides the needed interface:
>  > > 
>  > >  1. The sysfs interface.
>  > >  2. The structure and enumeration definition.
>  > >  3. The function firmware_map_add() and firmware_map_add_early()
>  > >     that should be called from architecture code (E820/EFI, for
>  > >     example) to add the contents to the interface.
>  > > 
>  > > If the kernel is compiled without CONFIG_FIRMWARE_MEMMAP, the interface does
>  > > nothing without cluttering the architecture-specific code with #ifdef's.
>  > > 
>  > 
>  > Hi Bernhard,
>  > 
>  > Thanks for the patch. Couple of thoughts.
>  > 
>  > Do we really need another CONFIG option (CONFIG_FIRMWARE_MEMMAP)? To,
>  > me this does not seem to be a big chunk of code
> 
> It should be configurable. Whether it's done via CONFIG_KEXEC or its own
> option I don't care.

Ok, changed:

diff --git a/drivers/firmware/Kconfig b/drivers/firmware/Kconfig
index 1008737..73fcc59 100644
--- a/drivers/firmware/Kconfig
+++ b/drivers/firmware/Kconfig
@@ -28,7 +28,7 @@ config EDD_OFF
 
 config FIRMWARE_MEMMAP
     def_bool y
-    depends on X86_64 || X86_32
+    depends on (X86_64 || X86_32) && KEXEC
 
 config EFI_VARS
        tristate "EFI Variable Support via sysfs"

I will wait with resending the patch for other feedback.


Bernhard
-- 
Bernhard Walle, SUSE LINUX Products GmbH, Architecture Development
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