Re: [seL4] Adding Platform Support: CAmkES-ARM-VM: VM_Minimal: Raspberry Pi 3b

20 Feb 2020

      Hi Shen,

I have managed to confirm that the frequency is 54MHz and the MAX_IRQ is 127.

Still no luck finding much on KERNEL_WCET, CLK_MAGIC or CLK_SHIFT so far. I’ll keep digging but any other tips you can throw my way would be appreciated!

Thanks,

Ben Turner

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From: Shen, Yanyan (Data61, Kensington NSW) 
Sent: 20 February 2020 03:55
To: Turner, Ben ; devel@sel4.systems
Cc: Millar, Curtis (Data61, Kensington NSW) ; Mcleod, Kent (Data61, Kensington NSW) 
Subject: Re: [seL4] Adding Platform Support: CAmkES-ARM-VM: VM_Minimal: Raspberry Pi 3b

Hi Ben,

You could also read the register CNTFRQ_EL0 [https://developer.arm.com/docs/ddi0595/b/aarch64-system-registers/cntfrq_el0https://developer.arm.com/docs/ddi0595/b/aarch64-system-registers/cntfrq_el0] to double check the value.

As to the max IRQ, you can read it from the GICD_TYPER [https://developer.arm.com/docs/ihi0048/b/arm-generic-interrupt-controller-ar...https://developer.arm.com/docs/ihi0048/b/arm-generic-interrupt-controller-ar...]. The ITLinesNumber field indicates the maximum number of interrupts supported by the GIC.

Hope that will help.

Regards,
Yanyan

From: "Turner, Ben" mailto:ben.turner@roke.co.uk>
Date: Thursday, 20 February 2020 at 3:06 am
To: "Shen, Yanyan (Data61, Kensington NSW)" mailto:Yanyan.Shen@data61.csiro.au>, "devel@sel4.systemsmailto:devel@sel4.systems" mailto:devel@sel4.systems>
Cc: "Millar, Curtis (Data61, Kensington NSW)" mailto:Curtis.Millar@data61.csiro.au>, "Mcleod, Kent (Data61, Kensington NSW)" mailto:Kent.Mcleod@data61.csiro.au>
Subject: RE: [seL4] Adding Platform Support: CAmkES-ARM-VM: VM_Minimal: Raspberry Pi 3b

Hi Shen,

Thanks for the advice. I may have found the TIMER_FREQUENCY (although I’m not certain) – the boot log has an entry:

    arch_timer: cp15 timer(s) running at 54.00MHz

This is the only possibly relevant timer reference I can find?

I haven’t had any luck with the MAX_IRQ value though. The only value in the boot log that could relate is:

    NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16

But 16 seems way lower than I would expect… The value for the RPi3, for example, is 127!

Thanks,

Ben Turner

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