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Re: [Xen-users] serial console to Dom0 -- connection, but only 'garbage' (� , 'question mark') output. config wrong?

  • To: pgnet.dev@xxxxxxxxx, Xen-users@xxxxxxxxxxxxx
  • From: Sarah Newman <srn@xxxxxxxxx>
  • Date: Fri, 31 Jan 2020 18:34:47 -0800
  • Delivery-date: Sat, 01 Feb 2020 02:35:11 +0000
  • Dkim-filter: OpenDKIM Filter v2.11.0 mail.prgmr.com 4CCAD72008A
  • List-id: Xen user discussion <xen-users.lists.xenproject.org>

On 1/31/20 6:24 PM, PGNet Dev wrote:
On 1/31/20 6:01 PM, Sarah Newman wrote:
That is correct usage.


You shouldn't expect the serial port you're asking Xen to use to be exposed in 

my goal here is to get all the server's boot logs -- kernel & xen -- into a remote 
terminal, as well as early access/control of BIOS & grub.

You have to go through hvc0 instead.

if "go through" hvc0 means writing to it (?),

checking, on the server

        dmesg | grep hvc
                [    1.823193] printk: console [hvc0] enabled
                [   21.773282] systemd[1]: Found device /dev/hvc0.
                [   50.136976] systemd[1]: Started Serial Getty on hvc0.

        stty -F /dev/hvc0
                speed 38400 baud; line = 0;
                min = 1; time = 0;
                -brkint -icrnl -imaxbel
                -isig -icanon -iexten -echo -echoe -echok -echoctl -echoke

not sure where that baud rate comes from -- or can be (re)set

attempting to change fails,

        /bin/stty -F /dev/hvc0 115200
                /bin/stty: /dev/hvc0: unable to perform all requested operations

and writes to it on server aren't making it to my desktop terminal at all -- 
whether 'minicom' baud rate is set to 115200 or 38400

i.e., on server,

        echo -e "test" > /dev/hvc0

succeeds (no error/hang), but NO data at desktop/minicom.

I *am* assuming this^^ is all the correct approach.  If not, what is?

Are you getting the Xen boot messages on minicom? That's where you should start.

Usually when I have problems with minicom it's because I forgot to disable flow 

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