Messages in this thread | | | Date | Thu, 2 Nov 2006 13:20:11 -0500 | From | Vivek Goyal <> | Subject | Re: [PATCH] x86_64: setup saved_max_pfn correctly (kdump) |
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On Fri, Nov 03, 2006 at 03:05:08AM +0900, Magnus Damm wrote: > Hi Mel, > > Thanks for your input! Great work with the add_active_range() code. > > On 11/3/06, Mel Gorman <mel@csn.ul.ie> wrote: > >Hey Magnus, > > > >I see what you are doing and why. However if you look in > >arch/x86_64/kernel/setup.c, you'll see > > > > parse_early_param(); > > > > finish_e820_parsing(); > > > > e820_register_active_regions(0, 0, -1UL); > > > >If you just called e820_register_active_regions(0, 0, -1UL) before > >parse_early_param(), would it still fix the problem without having to call > >e820_register_active_regions(0, 0, -1UL) twice? > > Well, I guess it is possible to move the > e820_register_active_regions() up, but I'm not sure if that would give > us anything. > > We need to call e820_register_active_regions() before e820_end_of_ram, > that's for sure, but the "exactmap" code in parse_memmap_opt() sets > e820.nr_map to 0 after the call to e820_end_of_ram(). Then it adds a > new set of user-supplied ranges to the e820 map which then need to be > registered using e820_register_active_regions(). > > So yeah, we can move the function up above parse_early_param() but > then we need to insert another call to e820_register_active_regions() > somewhere after all user-supplied ranges have been added. > > Another solution could be to rewrite e820_end_of_ram() to instead scan > e820.map[] backwards from e820.nr_map - 1 to locate the last ram page. > But can you do that in two lines of code? =) >
Is there are reason that why e820_end_of_ram() should be looking at active regions instead of dicrectly probing e820 memory map? If no, then modifying e820_end_of_ram() wil save us extra calls.
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