linux-kernel - Re: [PATCH v2 03/20] ARM: LPAE: use u32 instead of unsigned long for 32-bit ptes

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Message-id: <alpine.LFD.2.00.1011151707310.6448@xanadu.home>
Date:	Mon, 15 Nov 2010 17:11:50 -0500 (EST)
From:	Nicolas Pitre <nico@...xnic.net>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	Arnd Bergmann <arnd@...db.de>,
	Russell King - ARM Linux <linux@....linux.org.uk>,
	"linux-arm-kernel@...ts.infradead.org" 
	<linux-arm-kernel@...ts.infradead.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Will Deacon <will.deacon@....com>
Subject: Re: [PATCH v2 03/20] ARM: LPAE: use u32 instead of unsigned long for
 32-bit ptes

On Mon, 15 Nov 2010, Catalin Marinas wrote:

> On 15 November 2010 09:47, Arnd Bergmann <arnd@...db.de> wrote:
> > On Monday 15 November 2010 10:39:30 Catalin Marinas wrote:
> >> > There will be compiler warnings because u32 is unsigned int, and we
> >> > print it as %08lx.  Generic code cases pte values to (long long) and
> >> > prints them using %08llx.  We should do the same.
> >>
> >> We still need some kind of macro because with LPAE we need %016llx
> >> since the phys address can go to 40-bit and there are some additional
> >> bits in the top word. Unless you'd like to always print 16 characters
> >> even for 32-bit ptes (or if there is some other printk magic I'm not
> >> aware of).
> >
> > Why not just %010llx? That would just be two extra characters.
> 
> We still have attributes (like XN, bit 54) stored in the top part of
> the pte. This may be of interest when debugging.

They will be printed if they exist. The %010 in front of llx only means 
to have a minimum of 10 zero-paded digits if the value is smaller than 
that.

However, not having aligned values will be confusing.  A macro for the 
format might be the best compromize.


Nicolas