MESH SCSI driver not working

[Pol Vangheluwe]

On Fri, 2010-03-19 at 00:21 +0100, Stef Simoens wrote:
> Hello,
> 
> Some time ago (July 24th 2009 my mailbox says) I emailed you and the
> linuxppc-dev list about my problems booting from the mesh SCSI
> controller.
> 
> I just compiled 2.6.31 (actually, gentoo-sources-2.6.31-r10); but the
> problem remains
> I know that 2.6.33 is out, but as I didn't see any changes to the
> mesh-driver I guess that the problem is still there ...

Sadly I haven't had a chance to look. The MESH driver is a pretty
complicated thing that I didn't write and am not familiar with, so it's
going to take some work to sort out what's going on, and so far I
haven't had time to dedicate to this.

Cheers,
Ben.
I found this topic in the linuxppc-dev archives while googling for a mesh problem I currently have on my PowerPC 7500:
the boot process fails when populating /dev.  I think I have the same problem as reported by Stef Simoens: after a lot of complaints
like 'mesh_abort' and 'mesh_host_reset', it ends with Kernel panic about 'double DMA start'.

A rebuilt my kernel several times with different configs, but the only way to make it bootable is to disable the CDROM driver
(the 'sr' block of the SCSI upper layer).  The problem even occurs when 'sr' is built as a module.

My platform: pol [ ~ ]$ cat /proc/cpuinfo
processor	: 0
cpu		: 604e
clock		: 200.000000MHz
revision	: 2.4 (pvr 0009 0204)
bogomips	: 25.00
timebase	: 12500550
platform	: PowerMac
model		: Power Macintosh
machine		: Power Macintosh
motherboard	: AAPL,7500 MacRISC
detected as	: 16 (PowerMac 7500)
pmac flags	: 00000000
L2 cache	: 256K unified
pmac-generation	: OldWorld
Memory		: 208 MB

My kernel: pol [ ~ ]$ uname -a
Linux ppc7600 2.6.37.6 #4 Thu Aug 4 18:36:07 CEST 2011 ppc GNU/Linux

My compiler: pol [ ~ ]$ gcc -v       
Ingebouwde specs worden gebruikt.
COLLECT_GCC=gcc
COLLECT_LTO_WRAPPER=/usr/lib/gcc/powerpc-unknown-linux-gnu/4.5.2/lto-wrapper
Target: powerpc-unknown-linux-gnu
Configured with: ../gcc-4.5.2/configure --prefix=/usr --libexecdir=/usr/lib --enable-shared --enable-threads=posix --enable-__cxa_atexit --enable-clocale=gnu --enable-languages=c,c++ --disable-multilib --disable-bootstrap --with-system-zlib
Thread model: posix
gcc versie 4.5.2 (GCC) 

My system: LFS-2.8 (Linux From Scratch)

I have on the same machine also Ubuntu 8.04.1 (hardy), running the 2.6.24-19-powerpc kernel 
and gcc 4.1.3.  There is no mesh problem with this distribution.

Stef reported kernel 2.6.29 OK but 2.6.30-rcl and 2.6.31-rc3 NOK.

I recompiled mesh.c with DEBUG on and I see a lot of messages on the screen but I cannot capture them in a file.  We are too early
in the boot process for a working serial port and there is no disk mounted yet to log anything.

BenH was suspecting a DMA buffer misalignment but so far, I could not find a real solution on the Internet.
Anybody?

pvg

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