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From: David Howells <dhowells@redhat.com>
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To: Brian Norris <computersforpeace@gmail.com>
Subject: Re: roundup_pow_of_two() may not handle 64-bit integers
Date: Thu, 15 May 2014 16:03:09 +0100
Message-ID: <29314.1400166189@warthog.procyon.org.uk>
Cc: Linux Kernel <linux-kernel@vger.kernel.org>, dhowells@redhat.com,
 Paul Mackerras <paulus@samba.org>, Andrew Morton <akpm@linux-foundation.org>,
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Brian Norris <computersforpeace@gmail.com> wrote:

> I'm looking to use roundup_pow_of_two() (actually, order_base_2())
> from <linux/log2.h>, but it seems that it only supports 64-bit integers
> if your toolchain uses a 64-bit 'unsigned long' type. This is strange,
> considering that ilog2() is explicitly designed for 32-bit or 64-bit
> compatibility.

ilog2() was explicitly designed for use with 'unsigned long'.  See the commit
description (f0d1b0b30d250a07627ad8b9fbbb5c7cc08422e8).  It may work with
unsigned long long, however...

David