Re: [Xen-devel] Non readable output with XEN 4.4.3 serial console

[Pasi Kärkkäinen <pasik@xxxxxx>]

On Sat, Sep 26, 2015 at 08:17:05PM +0300, NiX wrote:
> Hi.
> 

Hi,

> As I posted about a week ago. I had an issue with an AMD FX-8350/Radeon
> 7970/Gigabyte GA-970A-UD3 and still do. After passing through the 7970, it
> works just fine on windows 10 for as long as I do not reboot/shutdown that
> VM.
> 
> Upon shutting down or rebooting the VM whole system becomes unresponsive.
> A full reboot of Dom0 is required in order to get passthrough working
> again without a system crash.
> 
> Someone suggested me to purchase a PCI serial card and I did. I can get
> linux serial console working without any issue including login via that
> console.
> 

Good.

> As soon as I enable XEN hvc0 in kernel boot params all I get is VGA
> console output though I did not enabled it via XEN boot params.
> 
> 
> A working one: GRUB_CMDLINE_LINUX="console=tty0 console=ttyS1,115200n81".
> A non working one: GRUB_CMDLINE_LINUX="console=hvc0" as suggested at
> http://wiki.xen.org/wiki/Xen_Serial_Console
> 

Please add "earlyprintk=xen nomodeset" for dom0 linux kernel aswell.. 
"console=hvc0 earlyprintk=xen nomodeset".


> dmesg | grep ttyS
> serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> 00:04: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> 0000:03:07.0: ttyS1 at I/O 0xc120 (irq = 21) is a 16550A --> Is a PCI
> serial card
> 
> GRUB_CMDLINE_XEN_DEFAULT="dom0_mem=4096M,max:8192M dom0_max_vcpus=4
> dom0_vcpus_pin iommu=1 loglvl=all guest_loglvl=all
> com1=115200,8n1,0xc120,21 console=com1"
> 

Did you try with "com1=115200,8n1,0xc120,0" ? So giving 0 as the irq.
Also try with lower speeds.. like 38400, and even 9600.

And dom0_mem should probably have the same value as initial and max.


> Wit the above line I only get non-readable output. I tried it pretty much
> all way around including different RTS/CTS options and 3 different tools
> and the result was always non-readable output
> 

With the correct options it'll work with Xen too.

Which program are you using to display/capture the serial console?


Thanks,

-- Pasi


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