On Thu, 27 Mar 2008 19:13:20 -0700
Jeremy Fitzhardinge <jeremy@xxxxxxxx> wrote:
Maybe no. but be carefull not to register resource in overlapped manner.OK. Would that ever be necessary if I explicitly align my start and size?Because, firmware may occupy some area in the section.Ah, ok. sorry.
Firmware must exclude those area to notify kernel. So, E820, EFI,
or _CRS of ACPI may return not aligned address and size.
register_memory_resource() and walk_memory_resource() are to skip
them silently. This is intended.
Jeremy, I think you can check whether you have 'struct page' or not by
pfn_valid().
If pfn_valid() == false, you should call add_memory() and create
a section/mem_map. If pfn_valid() == true, you should just remove
PG_reserved bit in mem_map by online_page().
(I wrote online_page() in above, but online_pages() is maybe better.
It does all what you want.)
Start/Size are automatically alined to section in __add_pages().
See below.
==
110 int __add_pages(struct zone *zone, unsigned long phys_start_pfn,
111 unsigned long nr_pages)
112 {
113 unsigned long i;
114 int err = 0;
115 int start_sec, end_sec;
116 /* during initialize mem_map, align hot-added range to section */
117 start_sec = pfn_to_section_nr(phys_start_pfn);
118 end_sec = pfn_to_section_nr(phys_start_pfn + nr_pages - 1);
==
And online_pages(), which onlines pages in [pfn, pfn + size), will see
registerred resources within [pfn, pfn + size).
==
184 int online_pages(unsigned long pfn, unsigned long nr_pages)
<snip>
227 walk_memory_resource(pfn, nr_pages, &onlined_pages,
228 online_pages_range);
==
One of my concern is how-to-handle sysfs status in this case.
Another concerns is, currently, I think no one tried to online a section twice
to online reserved pages in a section. so, you may see bug.
For example, mem_notify() in online_pages() will be called several times against
a section.