Re: [PATCH v3 13/17] ARM64 / ACPI: Add GICv2 specific ACPI boot support

Jon Masters
2014-09-09T06:36:30Z

On 09/03/2014 02:42 PM, Arnd Bergmann wrote:
> On Monday 01 September 2014 22:57:51 Hanjun Guo wrote:
>> + /* 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.