Re: [PATCH v3 1/2] ACPI: FPDT: expose FBPT and S3PT subtables via sysfs

Rafael J. Wysocki
2026-03-26T15:32:44Z

On Wed, Mar 25, 2026 at 12:17 AM Nate DeSimone
<nathaniel.l.desimone@intel.com> wrote:
>
> Add sysfs files at /sys/firmware/acpi/fpdt/FBPT and
> /sys/firmware/acpi/fpdt/S3PT that expose the raw contents of the
> FPDT subtables. Note that /sys/firmware/acpi/tables/FPDT only provides
> the top level table, not the subtables. Adding access to the subtables
> enables a usage model similar to /sys/firmware/dmi/tables/DMI, allowing
> userspace tools to interpret newer record types (e.g. String Event
> Records, Microcontroller Boot Performance Data Records, etc.) defined
> in recent ACPI specifications[1] without requiring kernel changes.
>
> [1]
> https://uefi.org/specs/ACPI/6.6/05_ACPI_Software_Programming_Model.html#performance-event-record-types
>
> Signed-off-by: Nate DeSimone <nathaniel.l.desimone@intel.com>
> ---
> drivers/acpi/acpi_fpdt.c | 28 ++++++++++++++++++++++++++++
> 1 file changed, 28 insertions(+)
>
> diff --git a/drivers/acpi/acpi_fpdt.c b/drivers/acpi/acpi_fpdt.c
> index 271092f2700a..e75dd28d31a9 100644
> --- a/drivers/acpi/acpi_fpdt.c
> +++ b/drivers/acpi/acpi_fpdt.c
> @@ -141,6 +141,9 @@ static const struct attribute_group boot_attr_group = {
> .name = "boot",
> };
>
> +static BIN_ATTR(FBPT, 0400, sysfs_bin_attr_simple_read, NULL, 0);
> +static BIN_ATTR(S3PT, 0400, sysfs_bin_attr_simple_read, NULL, 0);
> +
> static struct kobject *fpdt_kobj;
>
> #if defined CONFIG_X86 && defined CONFIG_PHYS_ADDR_T_64BIT
> @@ -254,9 +257,34 @@ static int fpdt_process_subtable(u64 address, u32 subtable_type)
> break;
> }
> }
> +
> + if (subtable_type == SUBTABLE_FBPT) {
> + bin_attr_FBPT.private = subtable_header;
> + bin_attr_FBPT.size = length;
> + result = sysfs_create_bin_file(fpdt_kobj, &bin_attr_FBPT);
> + if (result)
> + pr_warn("Failed to create FBPT sysfs attribute.\n");
> + } else if (subtable_type == SUBTABLE_S3PT) {
> + bin_attr_S3PT.private = subtable_header;
> + bin_attr_S3PT.size = length;
> + result = sysfs_create_bin_file(fpdt_kobj, &bin_attr_S3PT);
> + if (result)
> + pr_warn("Failed to create S3PT sysfs attribute.\n");
> + }
> +
> return 0;
>
> err:
> + if (bin_attr_FBPT.private) {
> + sysfs_remove_bin_file(fpdt_kobj, &bin_attr_FBPT);
> + bin_attr_FBPT.private = NULL;
> + }
> +
> + if (bin_attr_S3PT.private) {
> + sysfs_remove_bin_file(fpdt_kobj, &bin_attr_S3PT);
> + bin_attr_S3PT.private = NULL;
> + }
> +
> if (record_boot)
> sysfs_remove_group(fpdt_kobj, &boot_attr_group);
>
> --

Both patches applied as 7.1 material, thanks!