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

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

[rom.wang]

From: Yufeng Wang <wangyufeng@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.

Signed-off-by: Yufeng Wang <wangyufeng@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)) {
-- 
2.34.1

Re: [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@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@canonical.com>

> 
> Signed-off-by: Yufeng Wang <wangyufeng@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)) {

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

[Yao Zi]

On Thu, Mar 05, 2026 at 02:00:50PM +0100, Heinrich Schuchardt wrote:
> On 3/5/26 10:14, rom.wang wrote:
> > From: Yufeng Wang <wangyufeng@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.

I don't think so, this condition only decides whether an error is
printed as firmware bug when the kernel encountering pre-6.6 FADTs,
and the rest boot process should remain untouched. So it in fact breaks
nothing.

> 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@canonical.com>
> 
> > 
> > Signed-off-by: Yufeng Wang <wangyufeng@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);

Here pr_err() is the only statement enclosed by the if.

> >   	if (!(fadt->flags & ACPI_FADT_HW_REDUCED)) {

Reviewed-by: Yao Zi <me@ziyao.cc>

Regards,
Yao Zi

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

[Sunil V L]

On Thu, Mar 5, 2026 at 2:45 PM rom.wang <r4o5m6e8o@163.com> wrote:
>
> From: Yufeng Wang <wangyufeng@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.
>
> Signed-off-by: Yufeng Wang <wangyufeng@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);
>
LGTM. Thanks!

Reviewed-by: Sunil V L <sunilvl@oss.qualcomm.com>

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

[Paul Walmsley]

On Thu, 5 Mar 2026, rom.wang wrote:

> From: Yufeng Wang <wangyufeng@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.
> 
> Signed-off-by: Yufeng Wang <wangyufeng@kylinos.cn>

Thanks, queued for v7.1.


- Paul