Re: where is writable page table implemented?

[Tim Deegan <Tim.Deegan@citrix.com>]

At 11:37 -0400 on 01 Apr (1207049874), weiming wrote:
> Do you know under which situation we use writable page table instead of
> calling update_va_mapping?

Not in any detail.

> And do you know the purpose of the counter defined in
> page_info.u.in_use.type_info?
> I understand that xen needs to keep track of the type of each page
> (L1_page_table_page, L2_page_table_page, pinned, unpinned, validated, etc),
> but why do we need to use the lower 26 bits of "type_info" as a counter? (in
> "get_page_type()", the counter is increased. )  Similarly,  get_page() /
> put_page() also increases/decreases the page.count_info. Could you please
> give me some hint about the usage of such counters?

You should read the comments at the top of xen/arch/x86/mm.c.

Tim.

-- 
Tim Deegan <Tim.Deegan@citrix.com>
Principal Software Engineer, Citrix Systems (R&D) Ltd.
[Company #02300071, SL9 0DZ, UK.]