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From: Sowmini Varadhan <sowmini.varadhan@oracle.com>
To: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Cc: Guenter Roeck <linux@roeck-us.net>,
	linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
	benh@kernel.crashing.org, davem@davemloft.net
Subject: Re: [PATCH] iommu-common: Do not use 64 bit  constant 0xffffffffffffffffl for computing align_mask
Date: Sun, 19 Jul 2015 22:41:42 +0200	[thread overview]
Message-ID: <20150719204142.GA9844@oracle.com> (raw)
In-Reply-To: <874mkzevz4.fsf@rasmusvillemoes.dk>

On (07/19/15 22:25), Rasmus Villemoes wrote:
> 
> Wouldn't GENMASK(align_order-1, 0) work for all cases (assuming
> align_order has a sane value)?

Devices with limits on DMA masks are uncommon, so I'm personally
not an expert at all the variations in this space, but I was thinking
that this doing 

   align_mask = 0xffffffffffffffffull >> (64 - align_order); 

would be the compact answer for both 32 and 64 bit cases here? 

--Sowmini


  reply	other threads:[~2015-07-19 20:42 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2015-07-19 12:20 [PATCH] iommu-common: Do not use 64 bit constant 0xffffffffffffffffl for computing align_mask Sowmini Varadhan
2015-07-19 15:27 ` Guenter Roeck
2015-07-19 20:25   ` Rasmus Villemoes
2015-07-19 20:41     ` Sowmini Varadhan [this message]
2015-07-20  1:58     ` Guenter Roeck
2015-07-20 17:57       ` Rasmus Villemoes
2015-07-20 19:25         ` Sowmini Varadhan
2015-07-20 23:28         ` Andrew Morton
2015-07-21  0:26           ` Guenter Roeck
2015-07-20 14:44   ` Sowmini Varadhan

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