linux-kernel - Re: [PATCH 3/4] x86/insn: Extract more information about instructions

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Message-ID: <534FF43A.109@oracle.com>
Date:	Thu, 17 Apr 2014 11:33:14 -0400
From:	Sasha Levin <sasha.levin@...cle.com>
To:	Masami Hiramatsu <masami.hiramatsu.pt@...achi.com>
CC:	vegard.nossum@...cle.com, penberg@...nel.org,
	jamie.iles@...cle.com, hpa@...or.com, mingo@...hat.com,
	tglx@...utronix.de, x86@...nel.org, linux-kernel@...r.kernel.org,
	linux-mm@...r.kernel.org
Subject: Re: [PATCH 3/4] x86/insn: Extract more information about instructions

On 04/16/2014 01:44 AM, Masami Hiramatsu wrote:
> Same thing can be done in awk part and insn.c, and we can encode it by
> 
> #define INAT_MAKE_MEMSZ(size) (size << INAT_MEMSZ_OFFS)
> 
> And decode it by
> 
> insn->memsz_bytes = 1 << ((attr & INAT_MEMSZ_MASK) >> INAT_MEMSZ_OFFS)
> 
> Thus, we only need 3 bits to represent 1, 2, 4, 8, 16 and 32. :)

We'll need 4 so that we could do 64 too :)

btw, why aren't we using regular bitfields? this manual encoding
thingie seems to be a bit confusing (try figuring out how many
bits are left...).


Thanks,
Sasha
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