linux-kernel - RE: [RFC PATCH 02/10] acpi: install SSDT tables from initrd

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Message-ID: <1AE640813FDE7649BE1B193DEA596E883BB66712@SHSMSX101.ccr.corp.intel.com>
Date:	Tue, 5 Apr 2016 00:57:20 +0000
From:	"Zheng, Lv" <lv.zheng@...el.com>
To:	"Purdila, Octavian" <octavian.purdila@...el.com>
CC:	"Rafael J. Wysocki" <rjw@...ysocki.net>,
	Len Brown <lenb@...nel.org>,
	Matt Fleming <matt@...eblueprint.co.uk>,
	Mark Brown <broonie@...nel.org>,
	Wolfram Sang <wsa@...-dreams.de>,
	Joel Becker <jlbec@...lplan.org>,
	Christoph Hellwig <hch@....de>,
	"linux-acpi@...r.kernel.org" <linux-acpi@...r.kernel.org>,
	"linux-efi@...r.kernel.org" <linux-efi@...r.kernel.org>,
	"linux-i2c@...r.kernel.org" <linux-i2c@...r.kernel.org>,
	"linux-spi@...r.kernel.org" <linux-spi@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Tirdea, Irina" <irina.tirdea@...el.com>
Subject: RE: [RFC PATCH 02/10] acpi: install SSDT tables from initrd

Hi,

> From: linux-acpi-owner@...r.kernel.org [mailto:linux-acpi-
> owner@...r.kernel.org] On Behalf Of Octavian Purdila
> Subject: Re: [RFC PATCH 02/10] acpi: install SSDT tables from initrd
> 
> On Fri, Apr 1, 2016 at 8:05 AM, Zheng, Lv <lv.zheng@...el.com> wrote:
> > Hi,
> >
> > IMO, there is already a similar function upstreamed:
> >
> https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/commit/?id=c85c
> c81
> > Could it work for your use case?
> 
> Yes, it is basically the same.
> 
> The only difference is on how we handle taint. I think we should use a
> new taint for overlays and that we don't need to disable lockdep.
> 
> BTW, why is lockdep disabled when we override?
[Lv Zheng] 
I guess this is because of the old synchronization bugs.
Originally, the table handler may receive table events when the table is installed.
And that may trigger lock issues in such an early stage.

I don't think the acpi_table_taint() need to be there now.
The override mechanisms now happen in an initialization step before the tables are loaded.
It should be safe even the synchronization is not so robust in ACPICA.
Because during this step, all things are serial.
IMO, you can remove acpi_table_taint().

Thanks and best regards
-Lv


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