On Sun, 2012-09-30 at 17:28 -0600, Jason Gunthorpe wrote: > asm/page.h discusses the calculation for v2p and p2v, it should be: > va = pa + KERNELBASE - PHYSICAL_START > which is the same as: > va = pa + LOAD_OFFSET > > tophys/tovirt were using PAGE_OFFSET, which as page.h says, is almost > always the same thing. > > Signed-off-by: Jason Gunthorpe <jguntho...@obsidianresearch.com>
It's a bit gross tho in that KERNEL_BASE, PHYSICAL_START and LOAD_OFFSET are about where the kernel is linked/running, and while the value ends up happening to also be the p->v offset (and indeed not by accident), it makes the code less clear and more confusing. I think the main issue is that we did things wrong when implementing non-0 based setups. PAGE_OFFSET should have remained what its name implies which is the offset between p and v. I don't have the bandwidth to revisit all that, but I really think that whole are area where PAGE_OFFSET doesn't map 0 needs revisiting. Ben. > --- > arch/powerpc/include/asm/ppc_asm.h | 4 ++-- > 1 files changed, 2 insertions(+), 2 deletions(-) > > diff --git a/arch/powerpc/include/asm/ppc_asm.h > b/arch/powerpc/include/asm/ppc_asm.h > index ea2a86e..44edc3a 100644 > --- a/arch/powerpc/include/asm/ppc_asm.h > +++ b/arch/powerpc/include/asm/ppc_asm.h > @@ -461,14 +461,14 @@ END_FTR_SECTION_IFCLR(CPU_FTR_601) > #define fromreal(rd) tovirt(rd,rd) > > #define tophys(rd,rs) \ > -0: addis rd,rs,-PAGE_OFFSET@h; \ > +0: addis rd,rs,-LOAD_OFFSET@h; \ > .section ".vtop_fixup","aw"; \ > .align 1; \ > .long 0b; \ > .previous > > #define tovirt(rd,rs) \ > -0: addis rd,rs,PAGE_OFFSET@h; \ > +0: addis rd,rs,LOAD_OFFSET@h; \ > .section ".ptov_fixup","aw"; \ > .align 1; \ > .long 0b; \ _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
