[PATCH] x86: Quark: Add if/else to setup_arch for Quark TLB bug

Bryan O'Donoghue
2014-09-26T17:22:36Z

Quark X1000 incorrectly advertises PGE. In later the stages of boot
specifically in early_init_intel we setup_clear_cpu_cap for PGE.
At this point in time cpu_has_pge() will still be true.

Use the boot_cpu_data to decide if __flush_tlb_all() or __flush_tlb()
should be called subsequent to loading CR3

Signed-off-by: Bryan O'Donoghue <pure.logic@nexus-software.ie>
---
arch/x86/kernel/setup.c | 15 ++++++++++++++-
1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 41ead8d..8e61d5e 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -879,7 +879,20 @@ void __init setup_arch(char **cmdline_p)
KERNEL_PGD_PTRS);

load_cr3(swapper_pg_dir);
- __flush_tlb_all();
+
+ /*
+ * Flush the TLB after loading CR3
+ *
+ * Quark X1000 wrongly advertises PGE. Use boot_cpu_data to
+ * to make sure the TLB is flushed correctly in the early
+ * stage of setup_arch() for Quark X1000.
+ * X86_FEATURE_PGE flag is only setup later stage at
+ * early_cpu_init();
+ */
+ if (boot_cpu_data.x86 == 5 && boot_cpu_data.x86_model == 9)
+ __flush_tlb();
+ else
+ __flush_tlb_all();
#else
printk(KERN_INFO "Command line: %s\n", boot_command_line);
#endif
--
1.9.1