Subject: SA1100 PID based Virtual addressing

From: Larry Sendlosky <[email-masked]>
Date: Wed, 7 Oct 98 14:38:05 EDT

I believe somebody posted to the linux-arm list initially (I saw
all the traffic) concerning using the SA1100 as basis for some
O/S development. Somebody in group recalled a feature of the SA1100
and I don't remember seeing anybody else mention it here.

Coprocessor 15, Register 13 is Read/Write Process ID.

Bits 30-25 (PID) of this register are OR'd with bits 30-25 of
a virtual address. If the PID bits are non-zero, this effectively
remaps the virtual address to one of 64 chunks of VA space
in the lower 2GB.

larry

______________________________________________________________________
 Larry Sendlosky			 	            AMT
 [email-masked] (978) 506-4031                      Compaq
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From: Dirk Grunwald <[email-masked]>
Date: Thu, 8 Oct 1998 09:59:18 -0700 (PDT)

>>>>> "LS" == Larry Sendlosky <[email-masked]> writes:
LS> I believe somebody posted to the linux-arm list initially (I saw
LS> all the traffic) concerning using the SA1100 as basis for some
LS> O/S development. Somebody in group recalled a feature of the SA1100
LS> and I don't remember seeing anybody else mention it here.

LS> Coprocessor 15, Register 13 is Read/Write Process ID.

LS> Bits 30-25 (PID) of this register are OR'd with bits 30-25 of
LS> a virtual address. If the PID bits are non-zero, this effectively
LS> remaps the virtual address to one of 64 chunks of VA space
LS> in the lower 2GB.
--

Btw, this same feature will apparently be available in the SA120.