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Re: [PATCH 4/4] MTD: include ar7part in the list of partitions parsers

Subject: Re: [PATCH 4/4] MTD: include ar7part in the list of partitions parsers
From: Alexander Clouter <>
Date: Wed, 6 Jan 2010 20:28:10 +0000
References: <> <> <> <>
User-agent: tin/1.9.3-20080506 ("Dalintober") (UNIX) (Linux/2.6.26-2-sparc64-smp (sparc64))
In gmane.linux.ports.mips.general Florian Fainelli <> wrote:
>> [snipped]
>> It simply pulls apart the 'PROM' (aka ADAM2) config and uses that to
>> build the partition table.
> This is indeed simple but if I recall right the rationale behind ar7part was 
> to create a sane partition layout no matter if the bootloader was ADAM2 or 
> PSPBoot and the root filesystem type. JFFS2 and squashfs do not have the same 
> erase-block size alignment constraints, ar7part deals with that too.
I am not convinced that is a good idea, one main reason is ar7part.c has 
gotten terribly wrong the partition table ('loader' is too small[1] and 
'rootfs' overlaps with the 'linux' partition').

This is what I have from ADAM2's perspective:
Adam2_AR7WRD > printenv
mtd0                  0x900e0000,0x903f0000 <-- rootfs
mtd1                  0x90020000,0x900e0000 <-- kernel
mtd2                  0x90000000,0x90020000 <-- adam2 bootloader
mtd3                  0x903f0000,0x90400000 <-- configuration
mtd4                  0x90020000,0x903f0000 <-- kernel + rootfs

Linux spits out:
physmap platform flash device: 00800000 at 10000000
physmap-flash.0: Found 1 x16 devices at 0x0 in 16-bit bank
 Amd/Fujitsu Extended Query Table at 0x0040
physmap-flash.0: Swapping erase regions for broken CFI table.
number of CFI chips: 1
cmdlinepart partition parsing not available
RedBoot partition parsing not available
4 ar7part partitions found on MTD device physmap-flash.0
Creating 4 MTD partitions on "physmap-flash.0":
0x000000000000-0x000000010000 : "loader"
0x0000003f0000-0x000000400000 : "config"
0x000000020000-0x0000003f0000 : "linux"
0x0000000d0000-0x0000003f0000 : "rootfs"

My patch munched on whatever prom_getenv() returned, which from what I 
can tell looking at arch/mips/ar7/prom.c will work for both PSPBoot and 

Are there some strange mtd environment variables I am yet to see out in 
the wild or does my patch simply not work for PSPBoot primed kit?  If 
not can you give me some 'spiel' to play around with?


[1] okay, ADAM2 weighs in at less than 64kiB however it is not outside 
        the realm of possibility someone will port u-boot to AR7 which 
        would benefit from the full 128kiB of space?

Alexander Clouter
.sigmonster says: A man who turns green has eschewed protein.

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