ioremap() on ISA memory space

Geert Uytterhoeven Geert.Uytterhoeven at
Wed Jun 9 17:41:54 EST 1999

On Tue, 8 Jun 1999, Gabriel Paubert wrote:
> On Tue, 8 Jun 1999, Geert Uytterhoeven wrote:
> > I found one reason why current kernels don't work on my LongTrail: my NVRAM is
> > in ISA memory space. When the kernel tries to ioremap() it in
> > pmac_nvram_init(), I get
> > 
> >     __ioremap(): phys addr e0000 is RAM lr c000e43c
> > 
> > and ioremap() returns NULL, causing all later accesses to NVRAM (e.g. in atyfb)
> > to fail due to NULL pointer dereferences.
> > 
> > Do all CHRP boxes have NVRAM in ISA memory space? The comment (by Corey) near
> > the call to pmac_nvram_init() in chrp_init2() already wonders whether
> > pmac_nvram_init() should be called or not.
> I don't know, but according to M.Mares (the PCI guy), all addresses passed
> to ioremap should be processor physical addresses. So you should modify
> the call to ioremap to add the physical offset at which the ISA memory
> space (address 0-16 Mb) appears on the PCI bus. 

Oops, you're right (in my case that's an offset of 0xf7000000). Hence we have
to `fix up' the OF device tree first...



Geert Uytterhoeven                     Geert.Uytterhoeven at
Wavelets, Linux/{m68k~Amiga,PPC~CHRP}
Department of Computer Science -- Katholieke Universiteit Leuven -- Belgium

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