From: Russell King <rmk+lkml@arm.linux.org.uk>
To: Sam Ravnborg <sam@ravnborg.org>
Cc: Andi Kleen <andi@firstfloor.org>,
linux-arch@vger.kernel.org, ebiederm@xmission.com,
paulmck@linux.vnet.ibm.com, akpm@linux-foundation.org,
linux-kernel@vger.kernel.org
Subject: Re: [PATCH] [2/9] Add a kernel_address() that works for data too
Date: Tue, 5 Jan 2010 19:04:55 +0000 [thread overview]
Message-ID: <20100105190455.GE30868@flint.arm.linux.org.uk> (raw)
In-Reply-To: <20100105085853.GA28126@merkur.ravnborg.org>
On Tue, Jan 05, 2010 at 09:58:53AM +0100, Sam Ravnborg wrote:
> But you can trust _etext an almost all architectures.
> It is a bug if it is missing.
>
> So [_text, _etext] is the text section.
>
> The data section may be placed before or after - it depends on the architecture.
> But again - only some architectures define _sdata.
> But all? define _edata.
You can not guarantee that the data segment is after the text segment,
unless you want to outlaw XIP kernels. XIP kernels have the text
segment mapped at a completely different address to the data segment.
I'd suggest the only way to identify the data segment in a generic way
is to have everyone define _sdata, or more preferably _data (to be
consistent with _text), to be the start of the data segment.
--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of:
next prev parent reply other threads:[~2010-01-05 19:05 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20100105315.789846878@firstfloor.org>
2010-01-05 2:15 ` [PATCH] [2/9] Add a kernel_address() that works for data too Andi Kleen
2010-01-05 8:44 ` Russell King
2010-01-05 8:58 ` Sam Ravnborg
2010-01-05 19:04 ` Russell King [this message]
2010-01-05 19:15 ` Andi Kleen
2010-01-05 19:15 ` Andi Kleen
2010-01-08 23:51 ` Andrew Morton
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