[seL4] Question about IO ports in CAmKES

4 Oct 2017

      I have a question about the Real-time Clock component (RTC) for the x86 VMM
found here:

https://github.com/SEL4PROJ/global-components/blob/master/components/RTC/RTC...

Here is the text of the camkes file:

import <RTC.idl4>;
import <PutChar.idl4>;

component CMOS {
    hardware;
    provides IOPort cmos_address;
    provides IOPort cmos_data;
    attribute string cmos_address_attributes = "0x70:0x70";
    attribute string cmos_data_attributes = "0x71:0x71";

}

component RTC {
    provides RTC rtc;
    maybe uses PutChar putchar;
    uses IOPort cmos_address;
    uses IOPort cmos_data;
    attribute int heap_size = 0;

    /* Connect the hardware RTC to the RTC component */
    composition {
        component CMOS cmos;
        connection seL4HardwareIOPort rtc_cmos_address(from cmos_address,
to cmos.cmos_address);
        connection seL4HardwareIOPort rtc_cmos_data(from cmos_data, to
cmos.cmos_data);
    }
    configuration {
        cmos.cmos_address_attributes <- cmos_address_attributes;
        cmos.cmos_data_attributes <- cmos_data_attributes;
    }
}

What is the meaning of the last two statements in the configuration block?
what is the scoping rules for the "cmos_address_attributes" and
"cmos_data_attributes" variables? It looks like these attributes are
already set in the definition of the CMOS component? They seemed to be
assigned again in the configuration block?

- John

[seL4] Question about IO ports in CAmKES

John Backes