linux-kernel - [PATCH RFC] uio: allow use on nommu systems

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Message-ID: <20160715005306.GA16591@brightrain.aerifal.cx>
Date:	Thu, 14 Jul 2016 20:53:06 -0400
From:	Rich Felker <dalias@...c.org>
To:	"Hans J. Koch" <hjk@...sjkoch.de>,
	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Cc:	linux-kernel@...r.kernel.org
Subject: [PATCH RFC] uio: allow use on nommu systems

mmap of uio devices does not seem to work without further
nommu-specific support, but interrupt handling already works, and
userspace drivers for nommu systems can simply use physical mmio
addresses from userspace directly anyway without mmap.

Signed-off-by: Rich Felker <dalias@...c.org>
---

I don't particularly expect this to be accepted upstream as-is, but
since we're actually trying to use the UIO subsystem on nommu (J2),
I'd like to start a discussion of what an acceptable patch would
entail.

The uio_pdrv_genirq driver was tested on J2 with this patch and
interrupt handling works as expected.

 drivers/uio/Kconfig | 1 -
 1 file changed, 1 deletion(-)

diff --git a/drivers/uio/Kconfig b/drivers/uio/Kconfig
index 52c98ce..387b2bb 100644
--- a/drivers/uio/Kconfig
+++ b/drivers/uio/Kconfig
@@ -1,6 +1,5 @@
 menuconfig UIO
 	tristate "Userspace I/O drivers"
-	depends on MMU
 	help
 	  Enable this to allow the userspace driver core code to be
 	  built.  This code allows userspace programs easy access to
-- 
2.8.1