linux-kernel - Re: [PATCH 10/15] acpi: Export acpi_bus

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Date:   Wed, 31 Aug 2016 00:47:39 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     jeff.mcgee@...el.com
Cc:     isg-gms@...ists.intel.com,
        Ankitprasad Sharma <ankitprasad.r.sharma@...el.com>,
        "Rafael J. Wysocki" <rjw@...ysocki.net>,
        Len Brown <lenb@...nel.org>,
        ACPI Devel Maling List <linux-acpi@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 10/15] acpi: Export acpi_bus_type

On Tue, Aug 30, 2016 at 6:49 PM,  <jeff.mcgee@...el.com> wrote:
> From: Ankitprasad Sharma <ankitprasad.r.sharma@...el.com>
>
> Some modules, like i915.ko, needs to detect when certain ACPI features are
> active inorder to prevent corruption on contended resources.
> In particular, use of BIOS RapidStart Technology may corrupt the contents of
> the reserved graphics memory, due to unalarmed hibernation. In which case
> i915.ko cannot assume that it (reserved gfx memory) remains unmodified and
> must recreate the contents and importantly not use it to store unrecoverable
> user data.

The above doesn't explain why you need to export acpi_bus_type at all.

I suspect that this is in order to be able to do some hackish stuff on
it, so I'm not going to approve this patch as is.

> Signed-off-by: Ankitprasad Sharma <ankitprasad.r.sharma@...el.com>
> Cc: "Rafael J. Wysocki" <rjw@...ysocki.net>
> Cc: Len Brown <lenb@...nel.org>
> Cc: linux-acpi@...r.kernel.org
> Cc: linux-kernel@...r.kernel.org
> Signed-off-by: Jeff McGee <jeff.mcgee@...el.com>
> ---
>  drivers/acpi/scan.c | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/drivers/acpi/scan.c b/drivers/acpi/scan.c
> index 4b22ea8..7461bab 100644
> --- a/drivers/acpi/scan.c
> +++ b/drivers/acpi/scan.c
> @@ -1269,6 +1269,7 @@ struct bus_type acpi_bus_type = {
>         .remove         = acpi_device_remove,
>         .uevent         = acpi_device_uevent,
>  };
> +EXPORT_SYMBOL_GPL(acpi_bus_type);
>
>  static void acpi_device_del(struct acpi_device *device)
>  {
> --

Thanks,
Rafael