Re: [Qemu-devel] [RFC PATCH 07/11] hw/arm/virt-acpi-build: Generate FADT table and update ACPI headers

[Laszlo Ersek <lersek@redhat.com>]

comments below

On 01/24/15 10:21, Shannon Zhao wrote:
> FADT points to FACS and DSDT, in the case of mach virt, it is also used
> to set the Hardware Reduced bit and enable PSCI SMP booting through HVC.
> 
> Update the header definitions for FADT taking into account the new
> additions of ACPI v5.1 in `include/hw/acpi/acpi-defs.h`
> 
> Signed-off-by: Shannon Zhao <zhaoshenglong@huawei.com>
> ---
>  hw/arm/virt-acpi-build.c    |   26 ++++++++++
>  include/hw/acpi/acpi-defs.h |  114 +++++++++++++++++++++++++++++--------------
>  2 files changed, 103 insertions(+), 37 deletions(-)
> 
> diff --git a/hw/arm/virt-acpi-build.c b/hw/arm/virt-acpi-build.c
> index 2872dff..e3c708d 100644
> --- a/hw/arm/virt-acpi-build.c
> +++ b/hw/arm/virt-acpi-build.c
> @@ -218,6 +218,32 @@ build_gtdt(GArray *table_data, GArray *linker, VirtGuestInfo *guest_info)
>  static void
>  build_fadt(GArray *table_data, GArray *linker, uint64_t facs, uint64_t dsdt)
>  {
> +    AcpiFadtDescriptorRev5_1 *fadt = acpi_data_push(table_data, sizeof(*fadt));
> +
> +    /* Hardware Reduced = 1 and use PSCI 0.2+ and with HVC */

You set "Hardware Reduced" here.

> +    fadt->flags = cpu_to_le32(1 << ACPI_FADT_F_HW_REDUCED_ACPI);
> +    fadt->arm_boot_flags = cpu_to_le16((1 << ACPI_FADT_ARM_USE_PSCI_G_0_2) |
> +                                       (1 << ACPI_FADT_ARM_PSCI_USE_HVC));
> +
> +    /* ACPI v5.1 (fadt->revision.fadt->minor_revision) */
> +    fadt->minor_revision = 0x1;
> +
> +    fadt->Xfacs = cpu_to_le64(facs);

But you also set up a FACS table.

Hardware Reduced mode makes Linux ignore the FACS table. Please see
upstream kernel commit

commit 22e5b40ab21fcac21db0ff25fbb844ffecc73a4a
Author: Bob Moore <robert.moore@intel.com>
Date:   Wed Nov 16 10:57:28 2011 +0800

    ACPI 5.0: Implement hardware-reduced option

You can probably drop the generation of the FACS, unless you intend to
disable HW reduced mode.

Thanks
Laszlo