[hppa-linux] memory layout

[Mike Shaver]

Kumar wrote:
> 
> Talking about only pa1.1 or 32 bit CPUs, I would say the same layout
> can be used as Linux on Intel does. That is kernel mapped at 0xc0000000.
> So 3 Gig for User space and 1 Gig for kernel. Of course, other ppl may
> have different ideas.

OpenBSD has the same idea, it seems.  From
sys/arch/hppa/include/vmparam.h:

/* user/kernel map constants */
#define VM_MIN_ADDRESS          ((vm_offset_t)0)
#define VM_MAXUSER_ADDRESS      ((vm_offset_t)0xc0000000)
#define VM_MAX_ADDRESS          VM_MAXUSER_ADDRESS
#define VM_MIN_KERNEL_ADDRESS   ((vm_offset_t)0)
#define VM_MAX_KERNEL_ADDRESS   ((vm_offset_t)0xF0000000)

I'll start filling in the x86 numbers blindly, I guess.

> PA has this strange concept of Spaces and they have those
> space registers %sr0 to %sr7. This reminds me of Intel's segment
> registers. And whoever wanted to do any serious OS like Unix on 80386
> never liked segments.

Yeah, I've been trying to figure out whether we should do anything
special with those, but I don't quite understand the whole architecture
yet.

Mike

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