Re: [PATCH] ACPICA: make acpi_load_table() return table index

[Shevchenko, Andriy]

On Fri, Sep 13, 2019 at 05:20:21PM +0300, Moore, Robert wrote:
> -----Original Message-----
> From: Nikolaus Voss [mailto:nv@xxxxxxx] 
> Sent: Friday, September 13, 2019 12:44 AM
> To: Moore, Robert <robert.moore@xxxxxxxxx>
> Cc: Shevchenko, Andriy <andriy.shevchenko@xxxxxxxxx>; Schmauss, Erik <erik.schmauss@xxxxxxxxx>; Rafael J. Wysocki <rjw@xxxxxxxxxxxxx>; Len Brown <lenb@xxxxxxxxxx>; Jacek Anaszewski <jacek.anaszewski@xxxxxxxxx>; Pavel Machek <pavel@xxxxxx>; Dan Murphy <dmurphy@xxxxxx>; linux-acpi@xxxxxxxxxxxxxxx; devel@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; Ferry Toth <ftoth@xxxxxxxxxx>; nikolaus.voss@xxxxxxxxxxxxxxxxxxxxx
> Subject: RE: [PATCH] ACPICA: make acpi_load_table() return table index
> 
> Bob,
> 
> On Thu, 12 Sep 2019, Moore, Robert wrote:
> > The ability to unload an ACPI table (especially AML tables such as
> > SSDTs) is in the process of being deprecated in ACPICA -- since it is 
> > also deprecated in the current ACPI specification. This is being done 
> > because of the difficulty of deleting the namespace entries for the 
> > table.  FYI, Windows does not properly support this function either.
> 
> ok, I see it can be a problem to unload an AML table with all it's consequences e.g. with respect to driver unregistering in setups with complex dependencies. It will only work properly under certain conditions
> - nevertheless acpi_tb_unload_table() is still exported in ACPICA and we should get this working as it worked before.
> 
> AcpiTbUnloadTable is not exported, it is an internal interface only -- as
> recognized by the "AcpiTb".

In Linux it became a part of ABI when the

commit 772bf1e2878ecfca0d1f332071c83e021dd9cf01
Author: Jan Kiszka <jan.kiszka@xxxxxxxxxxx>
Date:   Fri Jun 9 20:36:31 2017 +0200

    ACPI: configfs: Unload SSDT on configfs entry removal

appeared in the kernel.

> I'm not sure that I want to change the interface
> to AcpiLoadTable just for something that is being deprecated. Already, we
> throw an ACPI_EXCEPTION if the Unload operator is encountered in the AML byte
> stream. The same thing with AcpiUnloadParentTable - it is being deprecated.
> 
>     ACPI_EXCEPTION ((AE_INFO, AE_NOT_IMPLEMENTED,
>         "AML Unload operator is not supported"));

-- 
With Best Regards,
Andy Shevchenko