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Commit 2efa33f8 authored by H. Peter Anvin's avatar H. Peter Anvin
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[x86 setup] Handle case of improperly terminated E820 chain 



At least one system (a Geode system with a Digital Logic BIOS) has
been found which suddenly stops reporting the SMAP signature when
reading the E820 memory chain.  We can't know what, exactly, broke in
the BIOS, so if we detect this situation, declare the E820 data
unusable and fall back to E801.

Also, revert to original behavior of always probing all memory
methods; that way all the memory information is available to the
kernel.

Signed-off-by: default avatarH. Peter Anvin <hpa@zytor.com>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: Joerg Pommnitz <pommnitz@yahoo.com>
parent bbc15f46

arch/i386/boot/memory.c

+23 −7
Original line number Diff line number Diff line
@@ -20,6 +20,7 @@ 


static int detect_memory_e820(void)

{

	int count = 0;

	u32 next = 0;

	u32 size, id;

	u8 err;
@@ -33,14 +34,24 @@ static int detect_memory_e820(void) 
		      "=m" (*desc)

		    : "D" (desc), "a" (0xe820));



		if (err || id != SMAP)

		/* Some BIOSes stop returning SMAP in the middle of

		   the search loop.  We don't know exactly how the BIOS

		   screwed up the map at that point, we might have a

		   partial map, the full map, or complete garbage, so

		   just return failure. */

		if (id != SMAP) {

			count = 0;

			break;

		}



		if (err)

			break;



		boot_params.e820_entries++;

		count++;

		desc++;

	} while (next && boot_params.e820_entries < E820MAX);

	} while (next && count < E820MAX);



	return boot_params.e820_entries;

	return boot_params.e820_entries = count;

}



static int detect_memory_e801(void)
@@ -89,11 +100,16 @@ static int detect_memory_88(void) 


int detect_memory(void)

{

	int err = -1;



	if (detect_memory_e820() > 0)

		return 0;

		err = 0;



	if (!detect_memory_e801())

		return 0;

		err = 0;



	if (!detect_memory_88())

		err = 0;



	return detect_memory_88();

	return err;

}