Messages in this thread | | | Date | Sat, 17 Jul 1999 17:27:32 +0100 (GMT) | From | Riley Williams <> | Subject | Re: Thinkpad 600 memory woes |
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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.
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