Regarding MPC8641D

Hello Bala,

I don't think the ioremap issues are related with low memory offset
mode. But again, I am not sure if you (system by default does not do it)
are reserving that area (from 256 to 512 which is low memory offset
region). Further, where do you get this 504 number specifically?

If you want, I can try out your code on my 8641D board.

Thanks
Siva


Date: Wed, 5 Dec 2007 17:45:01 -0800 (PST)
From: sivaji <redacted>
Subject: Re: Regarding MPC8641D
To: linuxppc-dev@ozlabs.org
Message-ID: [ref]
Content-Type: text/plain; charset=3Dus-ascii


Hi,
           We need only SMP mode, asper ur idea let me disable the Low
memory offset mode. We face some issues when ioremap in the kernel, we
guess
the problem is related to Low memory offset mode so only we go for that.
Consider now the Low memory offset is disable the bootargs
(root=3D/dev/ram
console=3DttyS0, mem=3D504M). When mem=3D504 or greater than  we are not =
able
to
ioremap, if mem is less than 500 there was no issues on ioremap. We
can't
understand why ioremap was failed for 504M?

Thanks and Regards
S.Balamurugan


Siva Prasad-3 wrote:

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Hi,
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If you want to use SMP, do not enable low memory offset mode. That is
only and only for AMP, not for SMP. All the exception vectors go into

a

different address range for core1, once you enable that, resulting in

a

need for entirely different copy of OS (be it Linux, or any other OS).
=20
You are in the right path. Just don't enable low memory offset mode,
unless you are looking for Assymetric multi-processing.
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- siva
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Message: 6
Date: Wed, 5 Dec 2007 16:45:31 -0800 (PST)
From: sivaji <redacted>
Subject: Re: Regarding MPC8641D
To: linuxppc-dev@ozlabs.org
Message-ID: [ref]
Content-Type: text/plain; charset=3Dus-ascii
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=20
Hai,
             The kernel was compiled in SMP mode. The low memory

offset

mode
is only for AMP mode means, then how we test both the core 0 and 1 in
the
linux kernel ?. Asper my understanding if we enable the Low Memory
Offset
mode, then only the core1 translation is enabled. If we disalbed the

Low

Memory offset mode, Only Core 0  will work in SMP mode and Core 1 will
idle.
If we want to test the efficient of Dual core means we need to enable
both
the core and Low Memory Offset Mode. For this configuration linux

kernel

was
not up.
( Please correct me if I am wrong )
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Thanks and Regards
Sivaji
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Chris Fester wrote:

quoted

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On Tue, 2007-12-04 at 23:51 -0800, sivaji wrote:

quoted

            We have designed  a MPC8641D based AMC card. We are

using

the

quoted

quoted

kernel (2.6.23-rc4) and uboot (1.2.0).  When we disable the core1

Low

quoted

quoted

Memory
offset mode the kernel was up and when we enable this core1 Low

Memory

quoted

quoted

offset mode kernel was not up, It was hang after MPIC

initialization.

quoted

[snip!]

quoted

                     After this the kernel was hang, i want to know

why

quoted

quoted

kernel was hang when we enalbe Low memory Offset mode. Please help

me

to

quoted

quoted

fix
this issue.

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Have you compiled your kernel for SMP mode?  I believe the Low memory
offset mode is only for AMP mode (vxworks can use this, probably

other

quoted

OSes).  I don't know if the kernel has support for any

multiprocessing

quoted

mode other than SMP.
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Hope that helps,
Chris
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