Re: kexec reboot code buffer

From: Martin J. Bligh (mbligh@aracnet.com)
Date: Mon Jan 27 2003 - 17:03:24 EST


>> The problem is that I have not figured out how to tell the memory
>> allocator just what I need,
> <snip>
>> I guess I would make the standard zones something like:
>> /*
>> * ZONE_DMA < 16 MB ISA DMA capable memory
>> * ZONE_NORMAL 16-896 MB direct mapped by the kernel
>> * ZONE_PHYSMEM 896-4096 MB memory that is accessible with the
>> MMU disabled.
>> * ZONE_HIGHMEM > 4096MB only page cache and user processes
>> */
>
> I think this might be overkill. ZONE_NORMAL gives you what you want,
> and I don't think it's worth it to introduce a new one just for the
> relatively short timespan where you have the new kernel loaded, but
> haven't actually shut down. I think a little comment next to the
> allocation explaining this will be more than enough.
>
> Martin, any ideas?

We talked about creating a new zone specifically for DMA32 (ie <4Gb)
for other reasons, but it's not there as yet. As Dave mentioned,
ZONE_NORMAL should be sufficient, though if you need it physically
contiguous, that might be a problem.

How much memory do you need? If it's only 2Mb or so, why don't we
statically reserve it at boot time and keep it set aside?

M.

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