linux-kernel - Re: [PATCH 06/28] nios2: Memory management

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Date:	Tue, 22 Apr 2014 12:35:22 -0300
From:	Ezequiel Garcia <ezequiel.garcia@...e-electrons.com>
To:	Tobias Klauser <tklauser@...tanz.ch>
Cc:	Ley Foon Tan <lftan@...era.com>, linux-arch@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
	lftan.linux@...il.com, cltang@...esourcery.com
Subject: Re: [PATCH 06/28] nios2: Memory management

On Apr 22, Tobias Klauser wrote:
> On 2014-04-22 at 16:24:43 +0200, Ezequiel Garcia <ezequiel.garcia@...e-electrons.com> wrote:
> > Hi Ley Foon,
> > 
> > On Apr 18, Ley Foon Tan wrote:
> > > +/*
> > > + * PAGE_SHIFT determines the page size
> > > + */
> > > +#define PAGE_SHIFT	12
> > > +#define PAGE_SIZE	4096
> > > +#define PAGE_MASK	(~(PAGE_SIZE - 1))
> > > +
> > 
> > How about something like this:
> > 
> > /* PAGE_SHIFT determines the page size */
> > #define PAGE_SHIFT              12
> > #define PAGE_SIZE               (_AC(1,UL) << PAGE_SHIFT)
> > #define PAGE_MASK               (~((1 << PAGE_SHIFT) - 1))
> > 
> > Otherwise, the PAGE_SIZE macro above produces some warnings, IIRC.
> 
> AFAIR old nios2 GCC versions (the 4.1 version from Windriver, IIRC)
> would complain about something like the above, that's the reason I added
> an explicit value for PAGE_SIZE back then.
> 

Other than being "pretty" the above fix is to remove a mismatch type
warning. You can get rid of the warning in different ways:

ifdef __ASSEMBLY__
define PAGE_SIZE       4096
else
define PAGE_SIZE       4096UL
endif

> I assume with the new nios2 GCC this should no longer be necessary and
> Ezequiel's fix should be fine.

Speaking of GCC... is there a libc available to test this kernel port?
(which I assume uses the generic syscall ABI)
-- 
Ezequiel García, Free Electrons
Embedded Linux, Kernel and Android Engineering
http://free-electrons.com
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