Minimal requirements to run L4linux using only a serial console

Masti Ramya Jayaram rmasti at inf.ethz.ch
Sat Aug 30 11:18:32 CEST 2014


Hi Martin,

I replied earlier to the list but I guess I messed it up a bit. Your tip on the polling turned out to be really helpful. I basically changed the type of serial_esc in kernel/fiasco/src/kern/config.cpp from SERIAL_ESC_IRQ to SERIAL_ESC_NOIRQ and it works! It would be great if you can elaborate on the difference  (I am guessing the latter uses a poll based system but more explanation would be great).

I was even able to run l4 and fiasco on the actual SCC hardware and get the UART RX to work. So thanks a ton for the tip! :)

Best,
Ramya 

________________________________________
From: Martin Schröder [mschroeder at web.de]
Sent: 29 August 2014 23:23
To: Masti  Ramya Jayaram; l4-hackers at os.inf.tu-dresden.de
Subject: Re: Minimal requirements to run L4linux using only a serial console

Hi Ramya,

Tx path of UART is working but the Rx part not due to missing
interrupts. In the Tx part interrupts are not really required - alt
least not for Hello World. I also don't care about the missing "H" right
now. So the first step would be polling the fiasco UART every 100ms or
so instead of waitung for interrupts.


Best regards,
    Martin


I don't care abount the missing "H", this could be anything.

Am 29.08.2014 17:45, Masti Ramya Jayaram schrieb:
> Hey Martin,
>
> No I just realized that ESC does not break into the debugger. But I can clearly see that the process instead of printing "Hello world" prints "ello World" :)
>
> What could the reason be?
>
> Thanks,
> Ramya
> ________________________________________
> From: l4-hackers [l4-hackers-bounces at os.inf.tu-dresden.de] on behalf of Martin Schröder [martin.schroeder at openlimit.com]
> Sent: 29 August 2014 17:35
> To: l4-hackers at os.inf.tu-dresden.de
> Subject: Re: Minimal requirements to run L4linux using only a serial console
>
> Hi Ramya,
>
> a: No, its not a must. The UART could also be polled (by a timer) to see if something arrived.
> b: At least regarding l4linux there is nothing more to it - afaik.
>
> But let's go back to the hello word example on the SCC. What happens if you press the <ESC> key? Does it break into the JDB debugger?
>
> Best regards,
>      Martin




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