[parisc-linux] Questions understanding exec_kernel
Hai Vo-Ba
hai@fc.hp.com
Wed, 22 Sep 1999 06:46:31 -0600 (MDT)
> .EXIT
> rfi ; begin execution of kernel.
> nop
> [Question: Page 5-139 from the PA-RISC 1.1 Architecture and Instruction
> Set Reference Manual states: "Execution of an RFI instruction when any
> of the PSW !, I, or R bits are ones is an undefined operation." We are
> explicitly setting the Q & I bits before calling the rfi command. I
> don't understand how this works ... ]
> .PROCEND
If I remember right, RFI followed by a NOP is an idiom to tell the CPU
to start fetching instructions from an absolute address pointed to by the
IVA so we usually want to that with interrupts enabled (Q & I bits set).
--Hai
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