Date: Thu, 17 Jul 2003 12:43:23 +0200
From: Andries Brouwer <aebr@win.tue.nl>
To: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andries Brouwer <aebr@win.tue.nl>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] print_dev_t for 2.6.0-test1-mm
Message-ID: <20030717124323.B2302@pclin040.win.tue.nl>
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In-Reply-To: <200307170300.UAA24096@cesium.transmeta.com>; from hpa@zytor.com on Wed, Jul 16, 2003 at 07:54:36PM -0700
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On Wed, Jul 16, 2003 at 07:54:36PM -0700, H. Peter Anvin wrote:

> > 16-bit only: 8:8, otherwise 32-bit only: 16:16, otherwise 32:32.
> 
> I would still recommend the arrangement for 64-bit dev_t that I posted
> a while ago:
> 
> dev_t<63:40> := major<31:8>
> dev_t<39:16> := minor<31:8>
> dev_t<15:8>  := major<7:0>
> dev_t<7:0>   := minor<7:0>

Yes, but we we also need to handle 32-bit dev_t incarnations.

> If you want, you can even make it 32-bit-friendly, although it makes
> it more complex; for example, this version would implement 32-bit with
> a 12:20 split:
> 
> dev_t<63:44> := major<31:12>
> dev_t<43:32> := minor<31:20>
> dev_t<31:28> := major<11:8>
> dev_t<27:16> := minor<19:8>
> dev_t<15:8>  := major<7:0>
> dev_t<7:0>   := minor<7:0>

Too messy. But you are right - no conditionals involved.

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