Chris Knadle wrote:
Gateway mini-desktop from
2001, AMI BIOS, Ubuntu 8.04.2 has GRUB in MBR, 384 MB RAM
(128+256). When BIOS has "Quick Boot Enabled" (quick RAM test,
etc.), no problem -- can run any OS from GRUB menu, all tests pass.
When "Quick Boot Disabled" in BIOS (more thorough RAM test and
maybe more tests), GRUB menu appears, but choosing anything
produces "Grub Error 28: Selected item could not fit into memory".
That's very interesting. That sounds like the more extended BIOS
memory test reserves a section of RAM that GRUB requires.
[snip]
Well, I'm sure there's a way to track down specifically what's
happening because the behavior is consistent. But off the top-of-my-
head this sounds more likely to be a buggy BIOS issue, because you get
a change in behavior based on a change in that alone.
Thanks, Chris! It does indeed look like a buggy BIOS. Thinking out
loud here:
MEM 0040h:0013h - BASE MEMORY SIZE IN KBYTES
Size: WORD
With "Quick Boot Enabled", the POST sets it to (decimal) 640 or 639, as
expected. With "Disabled" it's consistently getting set to (decimal)
447. That explains GRUB's error message.
Now memtest86+ v2.11 has found no errors in RAM from 132K up to the top
(384M), so it must not have found any error around 447K. Conclusion:
that value of 447 comes from a bug in the BIOS POST. With "Disabled" it
doesn't report any errors (apart from 447K base RAM), so it looks like
all the hardware is checking out okay by whatever tests it uses.
Therefore: I can either live with "Quick Boot Enabled" or look for a
newer BIOS, and apart from that one bit of code in the BIOS everything
is okay. Now I understand what is going on and why.
Interesting that code would still check that there's enough base memory,
as it's been nearly two decades since I saw a PC that did NOT have at
least 640K RAM.
Adam
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