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SubjectRe: Thinkpad 600 memory woes
Hi there.

>>> Try mem=127M. I forget what the issue was, but this worked
>>> for me. (Actually I used mem=95M with 96M of installed DRAM.)
>>> I think this was mentioned on one of the Thinkpad 600
>>> pages linked from the main linux-laptop page.

>> I believe the problem is that the BIOS really really wants to
>> have that last meg of memory reserved for itself, and it gets
>> cranky when the kernel overwrites what it's put there.

> Not at all. BIOS just need few KiBs (64 or 96 or may be 128) for
> shadowing ROM and so on so you can usually use 127.6 or may be
> even 127.8 but it does not worth it. It's not only Thinkpad --
> almost all PC's wil do this...

My experience has been that the BIOS's use the RAM that would
otherwise be mapped in the 640k-1M hole for shadowing, so that is not
the reason for this problem.

The two reasons I have met are as follows:

1. Some BIOS's grab a 4k block from the top of memory for their
own use. Simply specifying 4k less than the amount of RAM
present deals with this case.

2. Systems with on-board video that use main memory as video RAM
usually grab it from the top of main memory, but ONLY if the
on-board video is enabled. I've never used a system that went
and enabled it, but I would assume that one needed to reduce
the memory size by the amount of memory used for it.

Best wishes from Riley.

+----------------------------------------------------------------------+
| There is something frustrating about the quality and speed of Linux |
| development, ie., the quality is too high and the speed is too high, |
| in other words, I can implement this XXXX feature, but I bet someone |
| else has already done so and is just about to release their patch. |
+----------------------------------------------------------------------+
* ftp://ftp.MemAlpha.cx/pub/rhw/Linux
* http://www.MemAlpha.cx/kernel.versions.html


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