Re: [PATCH v4 09/14] cxl/acpi: Prepare use of EFI runtime services

Dave Jiang
2025-11-03T23:34:42Z

On 11/3/25 11:47 AM, Robert Richter wrote:
> In order to use EFI runtime services, esp. ACPI PRM which uses the
> efi_rts_wq workqueue, initialize EFI before CXL ACPI.
>
> There is a subsys_initcall order dependency if driver is builtin:
>
> subsys_initcall(cxl_acpi_init);
> subsys_initcall(efisubsys_init);
>
> Prevent the efi_rts_wq workqueue being used by cxl_acpi_init() before
> its allocation. Use subsys_initcall_sync(cxl_acpi_init) to always run
> efisubsys_init() first.
>
> Reported-by: Gregory Price <gourry@gourry.net>
> Tested-by: Joshua Hahn <joshua.hahnjy@gmail.com>
> Reviewed-by: Joshua Hahn <joshua.hahnjy@gmail.com>
> Reviewed-by: Gregory Price <gourry@gourry.net>
> Signed-off-by: Robert Richter <rrichter@amd.com>

Reviewed-by: Dave Jiang <dave.jiang@intel.com>> ---
> drivers/cxl/acpi.c | 8 ++++++--
> 1 file changed, 6 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cxl/acpi.c b/drivers/cxl/acpi.c
> index 1ab780edf141..a54d56376787 100644
> --- a/drivers/cxl/acpi.c
> +++ b/drivers/cxl/acpi.c
> @@ -996,8 +996,12 @@ static void __exit cxl_acpi_exit(void)
> cxl_bus_drain();
> }
>
> -/* load before dax_hmem sees 'Soft Reserved' CXL ranges */
> -subsys_initcall(cxl_acpi_init);
> +/*
> + * Load before dax_hmem sees 'Soft Reserved' CXL ranges. Use
> + * subsys_initcall_sync() since there is an order dependency with
> + * subsys_initcall(efisubsys_init), which must run first.
> + */
> +subsys_initcall_sync(cxl_acpi_init);
>
> /*
> * Arrange for host-bridge ports to be active synchronous with