linux-kernel - Re: [Part1 PATCH v5 07/22] x86, ACPI: Store override acpi tables phys addr in cpio files info array

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Date:	Mon, 17 Jun 2013 16:52:12 -0700
From:	Tejun Heo <tj@...nel.org>
To:	Tang Chen <tangchen@...fujitsu.com>
Cc:	tglx@...utronix.de, mingo@...e.hu, hpa@...or.com,
	akpm@...ux-foundation.org, trenn@...e.de, yinghai@...nel.org,
	jiang.liu@...wei.com, wency@...fujitsu.com, laijs@...fujitsu.com,
	isimatu.yasuaki@...fujitsu.com, mgorman@...e.de,
	minchan@...nel.org, mina86@...a86.com, gong.chen@...ux.intel.com,
	vasilis.liaskovitis@...fitbricks.com, lwoodman@...hat.com,
	riel@...hat.com, jweiner@...hat.com, prarit@...hat.com,
	x86@...nel.org, linux-doc@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	"Rafael J. Wysocki" <rjw@...k.pl>, linux-acpi@...r.kernel.org
Subject: Re: [Part1 PATCH v5 07/22] x86, ACPI: Store override acpi tables
 phys addr in cpio files info array

On Thu, Jun 13, 2013 at 09:02:54PM +0800, Tang Chen wrote:
> From: Yinghai Lu <yinghai@...nel.org>
> 
> This patch introduces a file_pos struct to store physaddr. And then changes
> acpi_initrd_files[] to file_pos type. Then store physaddr of ACPI tables
> in acpi_initrd_files[].
> 
> For finding, we will find ACPI tables with physaddr during 32bit flat mode
> in head_32.S, because at that time we don't need to setup page table to
> access initrd.
> 
> For copying, we could use early_ioremap() with physaddr directly before
> memory mapping is set.
> 
> To keep 32bit and 64bit platforms consistent, use phys_addr for all.

Also, how about something like the following?

Subject: x86, ACPI: introduce a new struct to store phys_addr of acpi override tables

ACPI initrd override table handling has been recently broken into two
functions - acpi_initrd_override_find() and
acpi_initrd_override_copy().  The former function currently stores the
virtual addresses and sizes of the found override tables in an array
of struct cpio_data for the latter function.

To make NUMA information available earlier during boot,
acpi_initrd_override_find() will be used much earlier - on 32bit, from
head_32.S before linear address translation is set up, which will make
it impossible to use the virtual addresses of the tables.

This patch introduces a new struct - file_pos - which records
phys_addr and size of a memory area, and replaces the cpio_data array
with it so that acpi_initrd_override_find() can record the phys_addrs
of the override tables instead of virtual addresses.  This will allow
using the function before the linear address is set up.

acpi_initrd_override_copy() now accesses the override tables using
early_ioremap() on the stored phys_addrs.

-- 
tejun
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