On 04/26/2010 06:25 PM, post@xxxxxxxx wrote:
Hi David,
please excuse me, i just couldn't resist to comment on this :-)
Some time ago we needed to handle multiple (virtual) address-spaces
(in TO_CAC/TO_UNCAC as well as in virt_to_phys and the like) for
SGI's Indigo2/R10k and Octane (neither could run a 32bit kernel).
So in addrspace.h we provided
#ifdef CONFIG_64BIT
static inline unsigned long kernel_physaddr(unsigned long kva)
{
if((kva&0xffffffff80000000UL)==0xffffffff80000000UL)
return CPHYSADDR(kva);
return XPHYSADDR(kva);
}
#else
#define kernel_physaddr CPHYSADDR
#endif
while mach-ipXX/spaces.h defined
#define TO_PHYS(x) ( kernel_physaddr(x))
#define TO_CAC(x) (CAC_BASE | kernel_physaddr(x))
#define TO_UNCAC(x) (UNCAC_BASE | kernel_physaddr(x))
which did the job.
But at that time these defines didn't meet much acceptance for general
use in 64bit kernels. Now, to my amusement, some modern processor
(and/or system) seems to urge this kind of address-handling again ;-)
FWIW, that seems cleaner than what I did (actually I didn't try my
code). That should be the default definition for 64-bit kernels I think.
David Daney
Good luck!
On Mon, 26 Apr 2010, David Daney wrote:
Date: Mon, 26 Apr 2010 10:19:04 -0700
From: David Daney<ddaney@xxxxxxxxxxxxxxxxxx>
To: wuzhangjin@xxxxxxxxx
Cc: Ralf Baechle<ralf@xxxxxxxxxxxxxx>,
Thomas Bogendoerfer<tsbogend@xxxxxxxxxxxxxxxx>,
linux-mips@xxxxxxxxxxxxxx
Subject: Re: [PATCH] MIPS: Calculate proper ebase value for 64-bit kernels
...
I don't think so. We should fix TO_UNCAC() so that it works with CKSEG0
addresses. It should be at physical address 0. So
TO_UNCAC(0xffffffff80000000), should yield 0x9000000000000000
#define TO_UNCAC(x) ({ \
u64 a = (u64)(x); \
if (a& 0xffffffffc000000 == 0xffffffff80000000) \
a = UNCAC_BASE | (a& 0x30000000); \
else \
a = UNCAC_BASE | (a& TO_PHYS_MASK) \
a; \
})
David Daney
...
