On Wed, 29 Mar 2017, Dou Liyang wrote:
> Now, there are two ways to setup local apic and io-apic in X86 arch:
> 1. In an SMP-capable system, it will be done when preparing the
> cpus in native_smp_prepare_boot_cpu().
> 2. If UP_LATE_INIT is y, it will be done in smp_init()
>
> And, there are many switches in kernel which can determine the way of
> APIC mode setup, as shown below:
>
> 1. kconfig :
> CONFIG_X86_64; CONFIG_X86_LOCAL_APIC; CONFIG_x86_IO_APIC
> 2. kernel option: disable_apic; skip_ioapic_setup
> 3. BIOS : boot_cpu_has(X86_FEATURE_APIC)
> 4. MP table: smp_found_config
> 5. ACPI: acpi_lapic; acpi_ioapic; nr_ioapic
>
> The setup is late which cause the dump-capture kernel hangs with 'notsc'
> option in 1st kernel option. and the use of these switches is messily.
>
> Before make the APIC mode setup earlier, construct a framework first to
> prepare for the work and make the logic clear.
Calling that a framework is slightly exaggerated. It's a selector function
for the interrupt delivery mode.
> #ifdef CONFIG_X86_X2APIC
> diff --git a/arch/x86/kernel/apic/apic.c b/arch/x86/kernel/apic/apic.c
> index f4fc949..bf4ccd0 100644
> --- a/arch/x86/kernel/apic/apic.c
> +++ b/arch/x86/kernel/apic/apic.c
> @@ -1153,6 +1153,63 @@ void __init sync_Arb_IDs(void)
> APIC_INT_LEVELTRIG | APIC_DM_INIT);
> }
>
> +enum apic_bsp_mode {
> + APIC_BSP_MODEL_PIC = 0,
> + APIC_BSP_MODEL_VIRTUAL_WIRE,
> + APIC_BSP_MODEL_SYMMETRIC_IO,
> + APIC_BSP_MODEL_COUNT
> +};
> +
> +static int __init apic_bsp_mode_check(void)
> +{
> +
> + /* Check kernel option */
> + if (disable_apic) {
> + pr_info("APIC disabled by kernel option\n");
kernel option is ambiguous. "APIC disabled via kernel command line" is telling
clearly where this comes from.
> + return APIC_BSP_MODEL_PIC;
> + }
> + /* Check BOIS */
> +#ifdef CONFIG_X86_64
> + /* On 64-bit, The APIC is integrated, So, must have APIC feature */
> + if (!boot_cpu_has(X86_FEATURE_APIC)) {
> + disable_apic = 1;
> + pr_info("Apic disabled by BIOS\n");
Please use APIC consistently.
> + return APIC_BSP_MODEL_PIC;
> + }
> +#else
> + if (!boot_cpu_has(X86_FEATURE_APIC) &&
> + APIC_INTEGRATED(boot_cpu_apic_version)) {
> + pr_err("BIOS bug, local APIC #%d not detected!...\n",
> + boot_cpu_physical_apicid);
Please make that
pr_err(FW_BUG, "Local APIC %d not detected, force emulation",
boot_cpu_physical_apicid);
and for consistency reasosns this should also set disable_apic to 1.
> + return APIC_BSP_MODEL_PIC;
> + }
> +#endif
> + /*
> + * Check MP table, if neither an integrated nor a separate chip
> + * doesn't exist.
> + */
> + if (!boot_cpu_has(X86_FEATURE_APIC) && !smp_found_config) {
> + pr_info("BOIS don't support APIC, and no SMP configuration.\n");
s/BOIS/BIOS/
and for consistency reasosns this should also set disable_apic to 1.
> + return APIC_BSP_MODEL_PIC;
> + }
> +
> + /* Check MP table, ps: if the virtual wire has been setup */
> + if (!smp_found_config) {
> + disable_ioapic_support();
> +
> + /* Check local APIC, if SMP_NO_CONFIG */
> + if (!acpi_lapic)
> + pr_info("SMP motherboard not detected\n");
> +
> + return APIC_BSP_MODEL_VIRTUAL_WIRE;
> + }
> +
> + /* Other checks of ACPI options will be done in each setup function */
> +
> + return APIC_BSP_MODEL_SYMMETRIC_IO;
> +}
> +
> /*
> * Setup the through-local-APIC virtual wire mode.
> */
> @@ -1202,6 +1259,22 @@ void apic_virture_wire_mode_setup(void)
> apic_write(APIC_LVT1, value);
> }
>
> +/* init the interrupt routing model for the BSP */
> +void __init init_bsp_APIC(void)
> +{
> + switch (apic_bsp_mode_check()) {
> + case APIC_BSP_MODEL_PIC:
> + pr_info("Keep in PIC mode(8259)\n");
> + return;
> + case APIC_BSP_MODEL_VIRTUAL_WIRE:
> + pr_info("switch to virtual wire model.\n");
Please consistenly start sentences with upper case letters.
Thanks,
tglx
