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Commit 45fbe3ee authored by Linus Torvalds's avatar Linus Torvalds Committed by Ingo Molnar
Browse files

x86, e820, pci: reserve extra free space near end of RAM 



The point is to take all RAM resources we have, and
_after_ we've added all the resources we've seen in
the E820 tree, we then _also_ try to add fake reserved
entries for any "round up to X" at the end of the RAM
resources.

[ Impact: improve PCI mem-resource allocation robustness, protect "stolen RAM" ]

Reported-by: default avatarYannick Roehlly <yannick.roehlly@free.fr>
Acked-by: default avatarJesse Barnes <jesse.barnes@intel.com>
Signed-off-by: default avatarYinghai Lu <yinghai@kernel.org>
Cc: Ivan Kokshaysky <ink@jurassic.park.msu.ru>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: yannick.roehlly@free.fr
LKML-Reference: <4A01A784.2050407@kernel.org>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
parent 134cbf35

arch/x86/kernel/e820.c

+35 −0
Original line number Diff line number Diff line
@@ -1371,6 +1371,23 @@ void __init e820_reserve_resources(void) 
	}

}



/* How much should we pad RAM ending depending on where it is? */

static unsigned long ram_alignment(resource_size_t pos)

{

	unsigned long mb = pos >> 20;



	/* To 64kB in the first megabyte */

	if (!mb)

		return 64*1024;



	/* To 1MB in the first 16MB */

	if (mb < 16)

		return 1024*1024;



	/* To 32MB for anything above that */

	return 32*1024*1024;

}



void __init e820_reserve_resources_late(void)

{

	int i;
@@ -1382,6 +1399,24 @@ void __init e820_reserve_resources_late(void) 
			insert_resource_expand_to_fit(&iomem_resource, res);

		res++;

	}



	/*

	 * Try to bump up RAM regions to reasonable boundaries to

	 * avoid stolen RAM:

	 */

	for (i = 0; i < e820.nr_map; i++) {

		struct e820entry *entry = &e820_saved.map[i];

		resource_size_t start, end;



		if (entry->type != E820_RAM)

			continue;

		start = entry->addr + entry->size;

		end = round_up(start, ram_alignment(start));

		if (start == end)

			continue;

		reserve_region_with_split(&iomem_resource, start,

						  end - 1, "RAM buffer");

	}

}



char *__init default_machine_specific_memory_setup(void)