On 09/03/2014 02:42 PM, Arnd Bergmann wrote:

On Monday 01 September 2014 22:57:51 Hanjun Guo wrote:

quoted

+       /* Collect CPU base addresses */
+       count = acpi_parse_entries(sizeof(struct acpi_table_madt),
+                                  gic_acpi_parse_madt_cpu, table,
+                                  ACPI_MADT_TYPE_GENERIC_INTERRUPT,
+                                  ACPI_MAX_GIC_CPU_INTERFACE_ENTRIES);
+       if (count < 0) {
+               pr_err("Error during GICC entries parsing\n");
+               return -EFAULT;
+       } else if (!count) {
+               /* No GICC entries provided, use address from MADT header */
+               struct acpi_table_madt *madt = (struct acpi_table_madt *)table;
+
+               if (!madt->address)
+                       return -EFAULT;
+
+               cpu_phy_base = (u64)madt->address;
+       }

After I read through ACPI-5.1 section 5.2.12.14, I wonder if this is the
best way to treat a missing ACPI_MADT_TYPE_GENERIC_INTERRUPT table.

Do we expect to see those in practice? It seems like using the x86 local
APIC address as a fallback for the GIC address is not something we
should do unless we absolutely have to support a system that doesn't
have the GIC table.

All GICv2 based ACPI systems should define GICCs for the CPU interfaces.

Jon.