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Re: Board reset

From: Peter Maydell
Subject: Re: Board reset
Date: Mon, 6 Jul 2020 10:29:16 +0100

On Sun, 5 Jul 2020 at 20:45, Mohannad Maklad <msala.work@gmail.com> wrote:
> How can I reset the controller at runtime? when I call the NVIC reset API it 
> just hangs inside an infinite loop waiting for reset. Any way would be OK, I 
> thought
> about executing "Execute 'mon system_reset'" But I didn't know how. I also 
> tried to find an address that maps NRST button but I also couldn't.

What specifically are you trying to do here, and what machine
model are you using? The QEMU model of the NVIC will assert
the "SYSRESETREQ" outbound GPIO when the guest writes to the
AIRCR asserting the SYSRESETREQ bit (and with the correct VECTKEY).
It's then up to the model of the specific machine to correctly
wire that up (typically to some code which calls
(This corresponds to real hardware, where for instance the
Cortex-M3 has a signal line "SYSRESETREQ" which it asserts
when AIRCR is written to, and it's up to the SoC that embeds
the CPU to make sure that a reset actually happens.)

Looking at the codebase I think we wire up the SYSRESETREQ
line correctly on some machine models but have forgotten it
for others. Which machine model are you using?

-- PMM

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