[seL4] Re: sel4 on bare-metal | Questions and comments

28 May 2022

      Thanks a lot Peter.
The issues were on my end.

Desktop
-----------
COM1 was the right port, but I was connecting the wrong physical connector
on the motherboard. After connecting the connector I am seeing output on
the port. However, the output is garbled, but it is the right amount of
output. Even the non-sel4 o/p is garbled, *so this is not a seL4 issue*.
If you have any insights on what could be happening here, that would be
great.

Looking at the serial_init()
https://github.com/seL4/seL4/blob/master/src/plat/pc99/machine/io.c#L15
function
in the kernel for pc99. I see that baudrate is 115200, with no parity and 1
stop bit.
Based on that I used the following picocom command:
...
picocom -b 115200 -p n -f n  -s 1 /dev/ttyUSB0
I tried different baudrates and settings, but no luck.

Server:
--------
I did not get a chance to try on a server. I will do that only if I cannot
make it work on the desktop.

Thanks again,
sid

On Thu, May 26, 2022 at 8:58 PM Peter Chubb  wrote:
...
[CAUTION: Non-UBC Email]
...
...
...
...
...
"Sid" == Sid Agrawal  writes:
Sid> x86_64 server ------------------ Spec: Dell R520, two quad-core
Sid> Xeons (E5-2407 v2 @ 2.40GHz), 32GB of memory.
Sid> The server's serial is redirected to the IPMI console. On the
Sid> IPMI console, I see many messages related to the bios, etc. And
Sid> finally, I see this:
The serial port redirected over IPMI is usually com2 not com1.
If you change the boot command to:
kernel mboot.c32
        append sel4kernel console_port=0x2f8 debug_port=0x2f8 ---
sel4rootserver
you may see the correct output.
Sid> x86_64 Desktop ---------------------- Spec: Core 2 Quad, 4 GB ram
Sid> Fortunately, even though the serial pins did not have any output,
Sid> the monitor output was the same as for the server. Unfortunately,
Sid> it did not get any farther along than the server.
Sid> MBR SYSLINUX 6.04 EDD [...]  Loading sel4kernel... ok Loading
Sid> rootserver... ok
Again, check *which* serial port you hooked up.  Booting linux, and
doing something like
  stty 115200 < /dev/ttyS0
  echo foo > /dev/ttyS0
will tell you if you have serial hooked up right.
Possibilities are:
 -- need to swap Rx and Tx lines on the connector
 -- talking to wrong port (com2 instead of com1)
Peter C
--
Dr Peter Chubb                https://trustworthy.systems/
Trustworthy Systems Group                        CSE, UNSW
Core hours: Mon 8am-3pm; Wed: 8am-5pm; Fri 8am-12pm.