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 <redacted>
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.
quoted hunk ↗ jump to hunk
---
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; \