Re: laptop problems
From: "David S. Zelinsky" <zelinsky@us.net>
> But with some experimenting, I
> discovered that telling the BIOS to disable both primary and secondary cache,
> I was able to get Linux to load, and all went well after that.
Turn it back on now, and see if it boots from hard disk with the cache on.
> 1) Does telling the BIOS to disable L1 and L2 cache have any affect on Linux?
Yes. The settings persist after BIOS hands control over to the boot loader.
> 2) Why was this preventing Linux from loading?
There are two problems that pop up. One has to do with some floppies
failing with the cache enabled and is poorly understood. The other
(more likely) has to do with many systems not invalidating the cache
contents when the A20 gate is asserted to change the system from real
to protected mode. This causes the kernel to die just after it starts
because it reads incorrect data out of the cache. If this is what is
happening try the "tecra" kernel, or build your own kernel as a
"zImage" rather than "bzImage".
> 3) What affect does not disabling shadow RAM? Does it just decrease the RAM
> available to Linux (/proc/meminfo does seem to report about 1.5 MB less than
> 16 MB I'm supposed to have)? Or can it cause more serious problems.
First, it's wasted because Linux doesn't spend much time executing code
in the ROMS that are shadowed. It might spend a little time in APM and some
32-bit BIOS functions, but not a significant amount. Second, if you have
shadow RAM mapped over I/O devices (many motherboards will do that if you
ask them to), accesses to those devices will not work. That RAM count does
not contain the memory that is below 1MB.
> 4) Is there any way to disable shadow RAM, if the BIOS setup doesn't offer it
> as an option? Is there any way to reclaim the lost RAM?
Only if you can get technical information on the chipset. A service manual
is the best bet, otherwise see what you can wheedle out of technical service.
> Another curiosity: When I went to run fips to shrink the win95 partition, I
> found, instead of just one large partition, there were four partitions: The
> first was almost the full 2 GB, the second and third were empty (zero length),
> and the fourth was 4 MB, but of "unknown" type. I was a little worried that
> some win95 feature was using that last partition, so I was afraid to delete
> it. Luckily I was able to shrink the first partition and put Linux swap and
> native partitions as the second and third, and leave the fourth alone.
That 4MB partition could be a boot manager partition, especially if you've
tried NT or have installed System Commander or its ilk. It might also be for
saving the system state when you suspend, but I'd expect it to be bigger
if that's the case. My Toshiba saves the state by continuing RAM power at
all times and does not use a disk partition for this.
Thanks
Bruce
--
Can you get your operating system fixed when you need it?
Linux - the supportable operating system. http://www.debian.org/support.html
Bruce Perens K6BP bruce@debian.org NEW PHONE NUMBER: 510-620-3502
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