From: "H. Peter Anvin" <hpa@zytor.com>
To: "Theodore Ts'o" <tytso@mit.edu>,
"H. Peter Anvin" <hpa@linux.intel.com>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
greg@kroah.com, w@1wt.eu, ewust@umich.edu, zakir@umich.edu,
mpm@selenic.com, nadiah@cs.ucsd.edu, jhalderm@umich.edu,
tglx@linutronix.de, davem@davemloft.net, mingo@kernel.org,
DJ Johnston <dj.johnston@intel.com>,
stable@vger.kernel.org
Subject: Re: [PATCH RFC] random: Account for entropy loss due to overwrites
Date: Tue, 16 Oct 2012 09:10:58 -0700 [thread overview]
Message-ID: <507D8712.4050008@zytor.com> (raw)
In-Reply-To: <20121016155307.GF17446@thunk.org>
On 10/16/2012 08:53 AM, Theodore Ts'o wrote:
>
> ... and it looks like include/linux/log2.h already has a definition
> for ilog2() which should definitely work for all versions of gcc, so
> we could do this instead:
>
> #define shiftbits(w) (ilog2((w)) + 5)
>
> /* x^128 + x^103 + x^76 + x^51 +x^25 + x + 1 -- 105 */
> { shiftbits(128), 103, 76, 51, 25, 1 },
> /* x^32 + x^26 + x^20 + x^14 + x^7 + x + 1 -- 15 */
> { shiftbits(32), 26, 20, 14, 7, 1 },
>
OK, works for me. I'll rev the patch later this week.
-hpa
prev parent reply other threads:[~2012-10-16 16:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-08-13 17:26 H. Peter Anvin
2012-08-15 19:30 ` Matt Mackall
2012-08-15 20:37 ` H. Peter Anvin
2012-09-29 19:47 ` H. Peter Anvin
2012-10-16 4:08 ` Theodore Ts'o
2012-10-16 4:45 ` H. Peter Anvin
2012-10-16 15:53 ` Theodore Ts'o
2012-10-16 16:10 ` H. Peter Anvin [this message]
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