[Etherboot-developers] Re: 1G memory limit and Etherboot

[<vas...@sy...>]

Peter Lister and I had recently some experiences with etherboot and initrd
because of a braindead BIOS. I haven't been able to try this scenario as the
machine I can have 1GB memory has the breandead BIOS, which can only report
upto 64MB extended memory.

So, here are my 2c:

I guess the kernel has been compiled to have only 1GB memory (as opposed to
2GB,4GB or other). In that case, the kernel uses a maximum of 960MB on 2.2
kernel, or 896MB on 2.4 kernel. Then initrd will be disabled as the kernel
sees that it extends beyond the available memory --- check the boot messages;
should be one of the very first lines.

The workarounds are to use the --rdbase option with mknbi as suggested
previously or compile the kernel with at least 2GB support. The latter will be
beneficial for other purposes as well any way.

If the problem proves to be as I described above, etherboot cannot
solve it other than the automatic choice of the initrd location to be lower
than 896MB. Then another option will be necessary to override that.

On the topic of memory, I have a suggestion for etherboot:
By default etherboot to override the amount of memory BIOS reports to be the
amount passed to the kernel in "mem=". There, of course, should be the option
of using BIOS's report even if "mem=" is given with the onus on the user to
get it right.

Vasil