Re: [PATCH] abstract out bits of ldt.c

[Zachary Amsden <zach@vmware.com>]

Chris Wright wrote:

>* Zachary Amsden (zach@vmware.com) wrote:
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>>Does Xen assume page aligned descriptor tables?  I assume from this 
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>Yes.
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>>patch and snippets I have gathered from others, that is a yes, and other 
>>things here imply that DT pages are not shadowed.  If so, Xen itself 
>>must have live segments in the GDT pages, so how do you allocate space 
>>for the per-CPU GDT pages on SMP?
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>early during boot.
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Doesn't that require 16 pages per CPU?  That seems excessive to impose 
on a native build.  Perhaps we could get away with 1 page per CPU for 
the GDT on native boots and bump that up to 16 if compiling for a 
virtualized sub-architecture - i.e. move GDT to a page aligned struct 
for native (doesn't cost too much), and give it MACH_GDT_PAGES of space 
which is defined by the sub-architecture.

Let's take this thread over to virtualization@lists.osdl.org as well.

Zach