Re: [Xen-users] Bug#708344: Serial Passthrough broken in Debian Wheezy?

[Jonas Meurer <jonas@xxxxxxxxxxxxxxx>]

Hello Ian,

first, thanks for the advices to further debug this issue. Your help is 
really appreciated!
Am 2013-06-05 12:11, schrieb Ian Campbell:
> Thanks. I'm taking this to xen-devel and moving the other two lists to
> bcc. For xen-devel the background can be found at
> http://bugs.debian.org/cgi-bin/bugreport.cgi?bug=708344
>
> The gist is that with:
>         irq         = [ 4 ]
>         ioports     = [ '3f8-3ff' ]
>
> in the guest config the serial port used to work with Jeremy's xen.git
> (used in Squeeze) but doesn't work with Wheezy (3.2 based) or a 3.9
> kernel. The smstools daemon fails with:
>         Cannot open serial port /dev/ttyS0, error: Function not 
> implemented
> Jonas' dmesg shows:
> [    0.196892] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    0.217565] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
>
> and /proc/ioports shows the region but /proc/interrupts does not 
> AFAICT.
> I can't see any interrupt related errors. Jonas can you confirm that 
> the
> dmesg includes the logs resulting from an attempt to open the device?
No, unfortunately I can not. With any new kernel (3.2 or 3.9), no 
messages appear in dmesg when either smsd or picocom try to connect to 
the serial port.
> Jonas, could you try a few more experiments, if you don't mind:
Sure. Unfortunately I don't have much experiences with serial ports, so 
you might need to give more advices.
> Can you use something simpler (like picocom) rather than smsdaemon and
> see if that works.
I tried to open with picocom ('picocom /dev/ttyS0'). It resulted in the 
following error output:
# picocom /dev/ttyS0
picocom v1.7

port is        : /dev/ttyS0
flowcontrol    : none
baudrate is    : 9600
parity is      : none
databits are   : 8
escape is      : C-a
local echo is  : no
noinit is      : no
noreset is     : no
nolock is      : no
send_cmd is    : sz -vv
receive_cmd is : rz -vv
imap is        :
omap is        :
emap is        : crcrlf,delbs,


FATAL: failed to add device /dev/ttyS0: Filedes is not a tty

> Assuming not could you strace it so we can see what
> is actually failing. If those attempts result in anything extra in the
> dmesg please can you post it.
I tried 'strace -o strace.log -ff -s 1024 -v smsd -u smsd -g dialout 
-t'. All resulting strace.log.* Logfiles are attached. I guess that 
strace.log.4521 is the interesting one. At least this is the only 
logfile that contains 'ttyS0'.
> It ought to be possible to set the port to polled mode, I think by
> setting the IRQ to -1 with setserial or I think it should be possible 
> on
> the command line but I can't seem to figure out how... Anyway, if you
> can get that to work it might be interesting...
Sorry, don't know nothing about this. What is 'polled mode'? I'm happy 
to do more testing, but would need more detailed advices ;)
Kind regards,
 jonas

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Attachment: strace.log.4517
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Attachment: strace.log.4521
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