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authorH. Peter Anvin <hpa@linux.intel.com>2012-09-24 19:05:48 -0400
committerH. Peter Anvin <hpa@linux.intel.com>2012-09-26 18:06:22 -0400
commit5a5a51db78ef24aa61a4cb2ae36f07f6fa37356d (patch)
tree22b37361c0d876beeea542f769fdb76444878b36 /arch/x86/realmode
parente139e95590dfebab81841bf7a3ac46500f51a47c (diff)
x86-32: Start out eflags and cr4 clean
%cr4 is supposed to reflect a set of features into which the operating system is opting in. If the BIOS or bootloader leaks bits here, this is not desirable. Consider a bootloader passing in %cr4.pae set to a legacy paging kernel, for example -- it will not have any immediate effect, but the kernel would crash when turning paging on. A similar argument applies to %eflags, and since we have to look for %eflags.id being settable we can use a sequence which clears %eflags as a side effect. Note that we already do this for x86-64. Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Link: http://lkml.kernel.org/r/1348529239-17943-1-git-send-email-hpa@linux.intel.com
Diffstat (limited to 'arch/x86/realmode')
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