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Re: [ts-7000] Reading memory using inline assemble causes segmentation f

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Subject: Re: [ts-7000] Reading memory using inline assemble causes segmentation fault
From: Anssi Kolehmainen <>
Date: Mon, 19 May 2008 02:42:50 +0300
On Sun, May 18, 2008 at 03:37:01PM -0000, carol9078 wrote:
> I'm alsot certainly missing the point, but why dows a simple memory
> read of the JP6 setting address not work and cause a segmntation fault
> and what can I do to fix it, I'm trying to write the smallest possible
> program to go in the initial ramdisk image to read the jumper on
> header 6 and decide which filesystem to boot on my TS7250, using the
> normal includes and statically linking results in a huge file (400K)
> so I thought I would try the inline assembler route:

Are you doing exactly the same thing? Is your C code only return
*((int*)JP6);? 

If I remember correctly then you need to do mmap() on /dev/mem before
you can access that part of memory. Normal usermode process doesn't have
that area mapped so it generates segfault.

Using kernel api directly with inline assembler might be trickey so you
might consider using uClibc (or similar). With that you get much smaller
statically linked executables.

-- 
Anssi Kolehmainen

040-5085390

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