linux-kernel - Re: [PATCH 2/2] ARM: xip: Use correct symbol for end of ROM marker

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Message-ID: <20150716161219.GL7557@n2100.arm.linux.org.uk>
Date:	Thu, 16 Jul 2015 17:12:19 +0100
From:	Russell King - ARM Linux <linux@....linux.org.uk>
To:	Chris Brandt <chris.brandt@...esas.com>
Cc:	arnd@...db.de, linux-arm-kernel@...ts.infradead.org,
	linux-kernel@...r.kernel.org, linux-sh@...r.kernel.org
Subject: Re: [PATCH 2/2] ARM: xip: Use correct symbol for end of ROM marker

On Thu, Jul 16, 2015 at 10:37:14AM -0400, Chris Brandt wrote:
> For an XIP build, _edata_loc, not _etext, is the end of constant R/O
> memory that needs to be mapped into the MODULES_VADDR area. This fixes
> the bug where you might loose part of your R/O data after page table
> setup is complete.

That's not correct.  _etext is set in the linker script to be the end of
the text + readonly data + exception table + unwinder tables + notes.
_edata_loc is the end address of the read/write data section stored in
read-only memory, which exists to be copied by the early kernel assembly
code to RAM.  There's no need for that to remain mapped.

I think you need to either provide more details of the problem you're
seeing, or further reasoning why this is a correct change.

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