diff options
author | H. Peter Anvin <hpa@linux.intel.com> | 2013-02-27 12:46:40 -0800 |
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committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-03-04 06:09:03 +0800 |
commit | 93b6b299f7a97a8ce2f8ab7b14195f8d2d131905 (patch) | |
tree | 356573809b3f31e742178d20611174010cde06d9 /arch/sh/mm | |
parent | 834f139f1613ba0ca3239a6a12be97c70698f189 (diff) |
x86: Make sure we can boot in the case the BDA contains pure garbage
commit 7c10093692ed2e6f318387d96b829320aa0ca64c upstream.
On non-BIOS platforms it is possible that the BIOS data area contains
garbage instead of being zeroed or something equivalent (firmware
people: we are talking of 1.5K here, so please do the sane thing.)
We need on the order of 20-30K of low memory in order to boot, which
may grow up to < 64K in the future. We probably want to avoid the
lowest of the low memory. At the same time, it seems extremely
unlikely that a legitimate EBDA would ever reach down to the 128K
(which would require it to be over half a megabyte in size.) Thus,
pick 128K as the cutoff for "this is insane, ignore." We may still
end up reserving a bunch of extra memory on the low megabyte, but that
is not really a major issue these days. In the worst case we lose
512K of RAM.
This code really should be merged with trim_bios_range() in
arch/x86/kernel/setup.c, but that is a bigger patch for a later merge
window.
Reported-by: Darren Hart <dvhart@linux.intel.com>
Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Matt Fleming <matt.fleming@intel.com>
Link: http://lkml.kernel.org/n/tip-oebml055yyfm8yxmria09rja@git.kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'arch/sh/mm')
0 files changed, 0 insertions, 0 deletions