The e820 probe code was checking %edx, not %eax, for the SMAP
signature on return. This worked on *almost* all systems, since %edx
still contained SMAP from the call on entry, but on a handful of
systems it failed -- plus, we would have missed real mismatches.
The error output is "=d" to make sure gcc knows %edx is clobbered
here.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
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: H. Peter Anvin <hpa@zytor.com>
Cc: Jordan Crouse <jordan.crouse@amd.com>
Cc: Joerg Pommnitz <pommnitz@yahoo.com>
Thomas Gleixner