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

Arnd Bergmann
2014-09-03T18:43:20Z

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.

Arnd