Intel Quark X1000 advertises PGE (bit 13 of EDX) in CPUID. In reality, it does not implement PGE in current silicon.
This is an issue because __flush_tlb_all() depends on cpu_has_pge which has following dependency: - cpu_has_pge --> boot_cpu_data --> new_cpu_data obtained from CPUID in head_32.S. On another note in reference to the below commit: x86/intel/quark: Switch off CR4.PGE so TLB flush uses CR3 instead The value of cpu_has_pge is updated to correctly reflect the capability for Quark later within early_init_intel() through setup_clear_cpu_cap(X86_FEATURE_PGE). So, future reference to __flush_tlb_all() is mapped to __flush_tlb(). As this is early stage of kernel boot-up and adding __flush_tlb() is not going to hurt much in CPU cycles, we add it here and together with the explanation for future reference. Signed-off-by: Ong Boon Leong <[email protected]> --- arch/x86/kernel/setup.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c index 41ead8d..90e0b85 100644 --- a/arch/x86/kernel/setup.c +++ b/arch/x86/kernel/setup.c @@ -880,6 +880,13 @@ void __init setup_arch(char **cmdline_p) load_cr3(swapper_pg_dir); __flush_tlb_all(); + /* + * Quark X1000 wrongly advertises PGE, add __flush_tlb() + * below to make sure 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(); + */ + __flush_tlb(); #else printk(KERN_INFO "Command line: %s\n", boot_command_line); #endif -- 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
