On Sunday, 2 October 2016 22:46:45 BST Masahiro Yamada wrote: > Hi Paul, > > 2016-10-01 23:19 GMT+09:00 Paul Burton <[email protected]>: > > README states that CONFIG_SYS_SDRAM_BASE should be the physical address > > of the base of SDRAM memory. This is expected by some code such as the > > PCI layer, which uses CONFIG_SYS_SDRAM_BASE to set up a region for > > system memory. Other code such as the image loading code used by bootm > > or the generic board_f.c expect CONFIG_SYS_SDRAM_BASE to be directly > > accessible by the CPU, which necessitates that it be a virtual address. > > > > Where virtual & physical addresses aren't identity mapped, as is the > > case for MIPS, we cannot possibly satisfy both. Until now MIPS has used > > a virtual CONFIG_SYS_SDRAM_BASE. This series fixes up the mess by doing > > > > a few things: > > - Ensuring that we provide virt_to_phys() on all architectures. > > > > - Fixing code that expects to use CONFIG_SYS_SDRAM_BASE as a virtual > > > > address to instead convert it to a physical address using > > virt_to_phys(). > > > > - Converts MIPS code & all MIPS boards to provide a physical > > > > CONFIG_SYS_SDRAM_BASE, which typically is zero. > > Thanks for working on this. > > As you may notice, include/linux/io.h defines > the generic implementation of ioremap(). > > (It is guarded by #ifndef CONFIG_HAVE_ARCH_IOREMAP > so that MIPS can work-around it.)
Hi Masahiro,
I hadn't actually noticed the generic ioremap - I suspect few do since you
don't get it by
including asm/io.h as you would in Linux. It'll also be wrong for other
architectures that
don't do a simple 1:1 physical:virtual translation but don't select
CONFIG_HAVE_ARCH_IOREMAP (nios2, sandbox).
> If you go with asm-generic/io.h,
> perhaps should we be consistent, that is,
> move the generic ioremap() to asm-generic/io.h?
>
> We do not have to do it in this series,
> but it would be appreciated
> if you volunteer to make it in a better way.
Yeah I'd be fine with cleaning that up, preferrably after this series is merged
so I don't have
more out of tree patches to juggle. I'd propose that we implement the generic
ioremap
atop map_physmem, which we ought to be able to do for every arch if we clean up
MIPS a
little.
Thanks,
Paul
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