linux-kernel - Re: [RFC PATCH 1/3] asm-generic: io: Add exec versions of ioremap

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Message-ID: <20160518205758.GY5783@n2100.arm.linux.org.uk>
Date:	Wed, 18 May 2016 21:57:59 +0100
From:	Russell King - ARM Linux <linux@...linux.org.uk>
To:	Arnd Bergmann <arnd@...db.de>
Cc:	Dave Gerlach <d-gerlach@...com>,
	linux-arm-kernel@...ts.infradead.org, linux-kernel@...r.kernel.org,
	linux-omap@...r.kernel.org, Russ Dill <russ.dill@...com>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	Shawn Guo <shawnguo@...nel.org>,
	Tony Lindgren <tony@...mide.com>,
	Alexandre Belloni <alexandre.belloni@...e-electrons.com>,
	Nishanth Menon <nm@...com>
Subject: Re: [RFC PATCH 1/3] asm-generic: io: Add exec versions of ioremap

On Wed, May 18, 2016 at 10:25:03PM +0200, Arnd Bergmann wrote:
> The ARM version of ioremap_exec() that gets added in this patch is cached
> (like memremap()), but then the asm-generic version is not? This is
> even more confusing, it should at least do roughly the same thing across
> architectures.
> 
> There should also be some documentation about what the expected behavior is, e.g.:
> 
> - is memremap_exec() by default cached or not? (I assume it would
>   be like memremap())
> - If we have an interface that does explicit uncached executable mapping,
>   what about architectures on which this is not possible? Should they
>   fall back to cached or non-executable, or cause a link error?  

Another important point is whether atomic instructions / kernel locks
can be located within the mapped memory.

-- 
RMK's Patch system: http://www.armlinux.org.uk/developer/patches/
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