Re: Kernel writes to RAM it doesn't own on 2.4.24

From: Richard B. Johnson
Date: Fri Apr 16 2004 - 11:57:01 EST

On Fri, 16 Apr 2004, Ross Biro wrote:

> mem= isn't there to tell the kernel what ram it owns and what ram it
> doesn't own. It's there to tell the kernel what ram is in the system.
> Since you told the system it only has 500m, it assumes the rest of
> the 3.5G of address space is available for things like memory mapped
> i/o. If you cat /proc/iomem, you'll probably see something has
> reserved the memory range in question.

No! This is address space, not RAM. Whether or not a PCI device
or whatever has internal RAM that's mapped makes no difference.

I told the kernel that it has 500m of RAM. It better not assume
I don't know what I'm talking about. I might have reserved that
RAM because it's bad or I may have something else important to
do with that RAM (which I do).

> I added a hack to make the kernel assume the greater of the mem= and
> what is passed to in from the BIOS via the e820 maps is where the
> unused address space starts. It seems to eliminate such problems.
> Ross
> On Fri, 16 Apr 2004 11:55:28 -0400 (EDT), Richard B. Johnson
> <root@xxxxxxxxxxxxxxxxxx> wrote:

Dick Johnson
Penguin : Linux version 2.4.24 on an i686 machine (5596.77 BogoMips).
Note 96.31% of all statistics are fiction.

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