RFC: Dynamic segment table allocation

[Anton Blanchard]

Hi,

> Can anyone see a problem with the patch below?  If not, I plan to push
> it to Andrew in the next few days.  Boots on a 4-way Power3 (RS/6000
> 270) and an RS64 iSeries lpar.
>
> PPC64 machines before Power4 need a segment table page allocated for
> each CPU.  Currently these are allocated statically in a big array in
> head.S for all CPUs.  However, except for the boot CPU, there are no
> particular constraints on the segment table's location, and the
> secondary CPUs don't come up until quite late when get_free_pages() is
> operational.
>
> This patch dynamically allocates segment table pages as the secondary
> CPUs come up.  This reduces the kernel image size by 192k...

I like the idea of removing this bloat. However I think all segment tables
have to be in the first segment, otherwise the bolted segment miss handler
could take a miss when storing to the segment table.

Anton

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