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Old 04-07-2011, 09:15 PM
Herton Ronaldo Krzesinski
Default x86, hibernate: Initialize mmu_cr4_features during boot

From: H. Peter Anvin <hpa@linux.intel.com>

Restore the initialization of mmu_cr4_features during boot, which was
removed without comment in checkin e5f15b45ddf3afa2bbbb10c7ea34fb32b6de0a0e

x86: Cleanup highmap after brk is concluded

thereby breaking resume from hibernate. This restores previous
functionality in approximately the same place, and corrects the
reading of %cr4 on pre-CPUID hardware (%cr4 exists if and only if
CPUID is supported.)

However, part of the problem is that the hibernate suspend/resume
sequence should manage the save/restore of %cr4 explicitly.

Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
Cc: Yinghai Lu <yinghai@kernel.org>
LKML-Reference: <201104020154.57136.rjw@sisk.pl>
(cherry picked from commit 4da9484bdece39ab0b098fa711e095e3e9fc8684)
Tested-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
BugLink: http://bugs.launchpad.net/bugs/752870
Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com>
arch/x86/kernel/setup.c | 5 +++++
1 files changed, 5 insertions(+), 0 deletions(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index e543fe9..4e59873 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1013,6 +1013,11 @@ void __init setup_arch(char **cmdline_p)
x86_init.paging.pagetable_setup_done(swapper_pg_di r);

+ if (boot_cpu_data.cpuid_level >= 0) {
+ /* A CPU has %cr4 if and only if it has CPUID */
+ mmu_cr4_features = read_cr4();
+ }
#ifdef CONFIG_X86_32
/* sync back kernel address range */
clone_pgd_range(initial_page_table + KERNEL_PGD_BOUNDARY,

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