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Subject: Re: [PATCH v2 05/25] powerpc/8xx: Fix vaddr for IMMR early remap
From: Scott Wood <scottwood@freescale.com>
To: Christophe Leroy <christophe.leroy@c-s.fr>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>, Paul Mackerras
 <paulus@samba.org>, Michael Ellerman <mpe@ellerman.id.au>,
 <linux-kernel@vger.kernel.org>, <linuxppc-dev@lists.ozlabs.org>
Date: Thu, 8 Oct 2015 14:13:28 -0500
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References: <cover.1442939410.git.christophe.leroy@c-s.fr>
 <83ffd345e7a3fe00443e32b6caf900e7618453d6.1442939410.git.christophe.leroy@c-s.fr>
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On Thu, 2015-10-08 at 14:34 +0200, Christophe Leroy wrote:
> Le 29/09/2015 01:39, Scott Wood a écrit :
> > On Tue, Sep 22, 2015 at 06:50:38PM +0200, Christophe Leroy wrote:
> > > Memory: 124428K/131072K available (3748K kernel code, 188K rwdata,
> > > 648K rodata, 508K init, 290K bss, 6644K reserved)
> > > Kernel virtual memory layout:
> > >    * 0xfffdf000..0xfffff000  : fixmap
> > >    * 0xfde00000..0xfe000000  : consistent mem
> > >    * 0xfddf6000..0xfde00000  : early ioremap
> > >    * 0xc9000000..0xfddf6000  : vmalloc & ioremap
> > > SLUB: HWalign=16, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
> > > 
> > > Mapping IMMR 1:1 is just wrong because it may overlap with another
> > > area. On most mpc8xx boards it is OK because IMMR is set to
> > > 0xff000000 but for instance on EP88xC board, IMMR is at 0xfa200000
> > > which overlaps with VM ioremap area
> > > 
> > > This patch fixes the virtual address for remapping IMMR to 0xff000000,
> > > regardless of the value of IMMR.
> > > 
> > > The size of IMMR area is 256kbytes (CPM at offset 0, security engine
> > > at offset 128) so 512kbytes is enough and allows to handle the EP88xC
> > > case (which is not 8Mbytes but only 2Mbytes aligned) the same way.
> > > 
> > > Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
> > Instead of hardcoding 0xff000000, can you use asm/fixmap.h to allocate a
> > virtual address at compile time?
> > 
> > 
> Yes good idea, but in asm/fixmap.h FIX_XXXX constants are defined as enums.
> Is there a way to use them in head_8xx.S ?

asm-offsets

-Scott