RE: How can I jump to non-linux address space?

From: Ian Thompson (ithompso@stargateip.com)
Date: Fri Oct 05 2001 - 19:38:53 EST


> Essentially, you have 2 choices:
>
> 1. Turn off the MMU.
> 2. insert a 1:1 physical to virtual mapping for the ROM and call the code.
> (with interrupts disabled).
>
> Which one works depends on what the ROM code requires.
>
> There is an example of (1) in the current ARM kernel sources - the RiscPC
> port uses this method to reboot - we can't activate the hardware reset
line
> on these machines, so our only option is to use this method.

I tried both of these, and I must be doing something wrong. For (1), I
grabbed the code you mentioned from the RiscPC port (setup_mm_for_reboot()
and some code from the soft reset routine). After calling
setup_mm_for_reboot, if I call __ioremap(), the processor hangs. If I shut
down the MMU, I get the same results.

Where would be a good place to find an example of how to implement your
second suggestion?

thanks. sorry to keep bothering you. i'll also try asking on the arm
newsgroup...
-ian

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