[PATCH] riscv: acpi: update FADT revision check to 6.6

[Heinrich Schuchardt]

On 3/5/26 10:14, rom.wang wrote:
> From: Yufeng Wang <wangyufeng at kylinos.cn>
> 
> ACPI 6.6 is required for RISC-V as it introduces RISC-V specific
> tables such as RHCT (RISC-V Hart Capabilities Table) and
> RIMT (RISC-V I/O Mapping Table).
> 
> Update the FADT revision check from 6.5 to 6.6 and remove
> the TODO comment since ACPI 6.6 has been officially released.

If I understand the change correctly:

After the patch QEMU v10.0.0 will stop to boot Linux via ACPI.
QEMU v10.1.0 will be supported as it indicates revision 6.6.
See function build_fadt_rev6() in qemu/hw/riscv/virt-acpi-build.c.

For Ubuntu this is not an issue as it is on QEMU 10.1 on recent releases 
(https://launchpad.net/ubuntu/+source/qemu).
Fedora 43 also has QEMU 10.1 
(https://packages.fedoraproject.org/pkgs/qemu/qemu/).
Suse Tumbleweed has 10.2.1 (https://software.opensuse.org/package/qemu).

Stable Debian Trixie using 10.0 will be impacted 
(https://packages.debian.org/trixie/qemu-system-misc). Debian Testing 
has 10.2.

Acked-by: Heinrich Schuchardt <heinrich.schuchardt at canonical.com>

> 
> Signed-off-by: Yufeng Wang <wangyufeng at kylinos.cn>
> ---
>   arch/riscv/kernel/acpi.c | 10 +++++-----
>   1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/arch/riscv/kernel/acpi.c b/arch/riscv/kernel/acpi.c
> index 71698ee11621..ff681db9f4f1 100644
> --- a/arch/riscv/kernel/acpi.c
> +++ b/arch/riscv/kernel/acpi.c
> @@ -85,12 +85,12 @@ static int __init acpi_fadt_sanity_check(void)
>   	 * The revision in the table header is the FADT's Major revision. The
>   	 * FADT also has a minor revision, which is stored in the FADT itself.
>   	 *
> -	 * TODO: Currently, we check for 6.5 as the minimum version to check
> -	 * for HW_REDUCED flag. However, once RISC-V updates are released in
> -	 * the ACPI spec, we need to update this check for exact minor revision
> +	 * ACPI 6.6 is required for RISC-V as it introduces RISC-V specific
> +	 * tables such as RHCT (RISC-V Hart Capabilities Table) and RIMT
> +	 * (RISC-V I/O Mapping Table).
>   	 */
> -	if (table->revision < 6 || (table->revision == 6 && fadt->minor_revision < 5))
> -		pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 6.5+\n",
> +	if (table->revision < 6 || (table->revision == 6 && fadt->minor_revision < 6))
> +		pr_err(FW_BUG "Unsupported FADT revision %d.%d, should be 6.6+\n",
>   		       table->revision, fadt->minor_revision);
>   
>   	if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {