Re: [PATCH] x86: enable x2apic early at the first point

From: Suresh Siddha
Date: Thu Feb 19 2009 - 17:15:31 EST


On Thu, 2009-02-19 at 13:50 -0800, Yinghai Lu wrote:
> Impact: fix bug.
>
> otherwise will get panic from early_acpi_boot_init()
> also make disable_x2apic global, so could use it it x2_apic_xxx.c
> and can get warning if preenabled system using nox2apic.
>
> Signed-off-by: Yinghai Lu <yinghai@xxxxxxxxxx>
>
> ---
> arch/x86/kernel/apic/apic.c | 3 +--
> arch/x86/kernel/apic/x2apic_cluster.c | 5 ++++-
> arch/x86/kernel/apic/x2apic_phys.c | 5 ++++-
> arch/x86/kernel/apic/x2apic_uv_x.c | 4 +++-
> drivers/pci/dmar.c | 3 ++-
> 5 files changed, 14 insertions(+), 6 deletions(-)
>
> Index: linux-2.6/arch/x86/kernel/apic/x2apic_cluster.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/x2apic_cluster.c
> +++ linux-2.6/arch/x86/kernel/apic/x2apic_cluster.c
> @@ -14,8 +14,11 @@ DEFINE_PER_CPU(u32, x86_cpu_to_logical_a
>
> static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
> {
> - if (cpu_has_x2apic)
> + if (cpu_has_x2apic && !disable_x2apic) {
> + x2apic = 1;
> + enable_x2apic();

Yinghai, I also ran into couple of x2apic issues on the latest tip and
this issue is one of them. I don't like this patch mainly because we are
enabling x2apic mode in the cpu, with out checking the intr-remapping
support. We should fall back to xapic mode (in a clean fashion) if there
is any issue with intr-remapping. So I am planning to post another patch
to fix this early hang issue that we both encountered.

thanks,
suresh

> return 1;
> + }
>
> return 0;
> }
> Index: linux-2.6/arch/x86/kernel/apic/x2apic_phys.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/x2apic_phys.c
> +++ linux-2.6/arch/x86/kernel/apic/x2apic_phys.c
> @@ -21,8 +21,11 @@ early_param("x2apic_phys", set_x2apic_ph
>
> static int x2apic_acpi_madt_oem_check(char *oem_id, char *oem_table_id)
> {
> - if (cpu_has_x2apic && x2apic_phys)
> + if (cpu_has_x2apic && !disable_x2apic && x2apic_phys) {
> + x2apic = 1;
> + enable_x2apic();
> return 1;
> + }
>
> return 0;
> }
> Index: linux-2.6/arch/x86/kernel/apic/x2apic_uv_x.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/x2apic_uv_x.c
> +++ linux-2.6/arch/x86/kernel/apic/x2apic_uv_x.c
> @@ -41,8 +41,10 @@ static int uv_acpi_madt_oem_check(char *
> uv_system_type = UV_LEGACY_APIC;
> else if (!strcmp(oem_table_id, "UVX"))
> uv_system_type = UV_X2APIC;
> - else if (!strcmp(oem_table_id, "UVH")) {
> + else if (!strcmp(oem_table_id, "UVH") && !disable_x2apic) {
> uv_system_type = UV_NON_UNIQUE_APIC;
> + x2apic = 1;
> + enable_x2apic();
> return 1;
> }
> }
> Index: linux-2.6/arch/x86/kernel/apic/apic.c
> ===================================================================
> --- linux-2.6.orig/arch/x86/kernel/apic/apic.c
> +++ linux-2.6/arch/x86/kernel/apic/apic.c
> @@ -116,11 +116,10 @@ __setup("apicpmtimer", setup_apicpmtimer
> int x2apic;
> /* x2apic enabled before OS handover */
> static int x2apic_preenabled;
> -static int disable_x2apic;
> +int disable_x2apic;
> static __init int setup_nox2apic(char *str)
> {
> disable_x2apic = 1;
> - setup_clear_cpu_cap(X86_FEATURE_X2APIC);
> return 0;
> }
> early_param("nox2apic", setup_nox2apic);
> Index: linux-2.6/drivers/pci/dmar.c
> ===================================================================
> --- linux-2.6.orig/drivers/pci/dmar.c
> +++ linux-2.6/drivers/pci/dmar.c
> @@ -472,7 +472,8 @@ void __init detect_intel_iommu(void)
> * is added, we will not need this any more.
> */
> dmar = (struct acpi_table_dmar *) dmar_tbl;
> - if (ret && cpu_has_x2apic && dmar->flags & 0x1)
> + if (ret && cpu_has_x2apic && !disable_x2apic &&
> + dmar->flags & 0x1)
> printk(KERN_INFO
> "Queued invalidation will be enabled to support "
> "x2apic and Intr-remapping.\n");

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