DomU console driver not works for Fedora17 in HVM mode with Xen 4.1.2

[Wei Xu]

> Hi All,
> I'm try to set up and verify Xen console driver base on Fedora 17 and Xen
> 4.1.2 with hvm guest mode,
> i searched around and got a link, it give steps both for PV and HVM mode,
> I followed the HVM guide
> and upgraded my kernel to 3.5.0.
>        http://www.dedoimedo.com/computers/xen-console.html
>
> After that, I can got console output with "xm console <dom_id>", but the
> console driver is not used when I tracing the driver
> with "crash" utility, by examing the "console_drivers", the console driver
> is still "serial8250 console", so i wonder if I didn't
> set up it properly or something else, is there someone ever experienced
> it, thanks.
>
> crash> p *console_drivers
> $10 = {
>   name = "ttyS\000\000\000\000\000\000\000\000\000\000\000",
>   write = 0xffffffff8138d5a0 <serial8250_console_write>,
>   read = 0,
>   device = 0xffffffff8138c350 <uart_console_device>,
>   unblank = 0,
>   setup = 0xffffffff81d29926 <serial8250_console_setup>,
>   early_setup = 0xffffffff8138ca10 <serial8250_console_early_setup>,
>   flags = 22,
>   index = 0,
>   cflag = 0,
>   data = 0xffffffff81c82640,
>   next = 0x0
> }
>
> Thanks,
> Wei

[Konrad Rzeszutek Wilk]

On Mon, Aug 20, 2012 at 09:39:56PM +0800, Wei Xu wrote:
> > Hi All,
> > I'm try to set up and verify Xen console driver base on Fedora 17 and Xen
> > 4.1.2 with hvm guest mode,
> > i searched around and got a link, it give steps both for PV and HVM mode,
> > I followed the HVM guide
> > and upgraded my kernel to 3.5.0.
> >        http://www.dedoimedo.com/computers/xen-console.html
> >
> > After that, I can got console output with "xm console <dom_id>", but the
> > console driver is not used when I tracing the driver

.. I am not sure I understand: "when I tracing the driver" ? Are
you referring to the PV driver?
> > with "crash" utility, by examing the "console_drivers", the console driver
> > is still "serial8250 console", so i wonder if I didn't
> > set up it properly or something else, is there someone ever experienced
> > it, thanks.

Hm, it should be the hvc one. Perhaps Stefano knows..

CC-ing him and xen-devel here.
> > crash> p *console_drivers
> > $10 = {
> >   name = "ttyS\000\000\000\000\000\000\000\000\000\000\000",
> >   write = 0xffffffff8138d5a0 <serial8250_console_write>,
> >   read = 0,
> >   device = 0xffffffff8138c350 <uart_console_device>,
> >   unblank = 0,
> >   setup = 0xffffffff81d29926 <serial8250_console_setup>,
> >   early_setup = 0xffffffff8138ca10 <serial8250_console_early_setup>,
> >   flags = 22,
> >   index = 0,
> >   cflag = 0,
> >   data = 0xffffffff81c82640,
> >   next = 0x0
> > }
> >
> > Thanks,
> > Wei
> --
> xen mailing list
> [e-mail]
> https://admin.fedoraproject.org/mailman/listinfo/xen

[Wei Xu]

Thanks.

On Monday, August 20, 2012, Konrad Rzeszutek Wilk wrote:
> On Mon, Aug 20, 2012 at 09:39:56PM +0800, Wei Xu wrote:
> > > Hi All,
> > > I'm try to set up and verify Xen console driver base on Fedora 17 and
>
> Xen
> > > 4.1.2 with hvm guest mode,
> > > i searched around and got a link, it give steps both for PV and HVM
>
> mode,
> > > I followed the HVM guide
> > > and upgraded my kernel to 3.5.0.
> > >        http://www.dedoimedo.com/computers/xen-console.html
> > >
> > > After that, I can got console output with "xm console <dom_id>", but
>
> the
> > > console driver is not used when I tracing the driver
>
> .. I am not sure I understand: "when I tracing the driver" ? Are
> you referring to the PV driver?

No, i mean the hvm driver, I add some debug info to hvm console read/write
function
but it never be invoked, then I exam the "console_drivers" and found no hvm
like driver was
registered.
> > > with "crash" utility, by examing the "console_drivers", the console
>
> driver
> > > is still "serial8250 console", so i wonder if I didn't
> > > set up it properly or something else, is there someone ever experienced
> > > it, thanks.
>
> Hm, it should be the hvc one. Perhaps Stefano knows..
>
> CC-ing him and xen-devel here.
> > > crash> p *console_drivers
> > > $10 = {
> > >   name = "ttyS\000\000\000\000\000\000\000\000\000\000\000",
> > >   write = 0xffffffff8138d5a0 <serial8250_console_write>,
> > >   read = 0,
> > >   device = 0xffffffff8138c350 <uart_console_device>,
> > >   unblank = 0,
> > >   setup = 0xffffffff81d29926 <serial8250_console_setup>,
> > >   early_setup = 0xffffffff8138ca10 <serial8250_console_early_setup>,
> > >   flags = 22,
> > >   index = 0,
> > >   cflag = 0,
> > >   data = 0xffffffff81c82640,
> > >   next = 0x0
> > > }
> > >
> > > Thanks,
> > > Wei
> > --
> > xen mailing list
> > [e-mail] javascript:;
> > https://admin.fedoraproject.org/mailman/listinfo/xen

[Stefano Stabellini]

On Mon, 20 Aug 2012, Konrad Rzeszutek Wilk wrote:
> On Mon, Aug 20, 2012 at 09:39:56PM +0800, Wei Xu wrote:
> > > Hi All,
> > > I'm try to set up and verify Xen console driver base on Fedora 17 and Xen
> > > 4.1.2 with hvm guest mode,
> > > i searched around and got a link, it give steps both for PV and HVM mode,
> > > I followed the HVM guide
> > > and upgraded my kernel to 3.5.0.
> > >        http://www.dedoimedo.com/computers/xen-console.html
> > >
> > > After that, I can got console output with "xm console <dom_id>", but the
> > > console driver is not used when I tracing the driver
>
> .. I am not sure I understand: "when I tracing the driver" ? Are
> you referring to the PV driver?
> > > with "crash" utility, by examing the "console_drivers", the console driver
> > > is still "serial8250 console", so i wonder if I didn't
> > > set up it properly or something else, is there someone ever experienced
> > > it, thanks.
>
> Hm, it should be the hvc one. Perhaps Stefano knows..
>
> CC-ing him and xen-devel here.

An HVM guest has access to both an emulated serial (if a serial="pty"
parameter is present in the VM config file) and a PV console.
However the default first console is the emulated serial with libxl (see
libxl__primary_console_find), that is what you get when you execute "xl
console" without -t.

But if you edit inittab to spawn a getty on hvc0 and then execute "xl
console -t pv" you should get access to the PV console.

[Wei Xu]

Thanks for your reply.

I have tried the method but it looks still can't work, there is no "hvc0"
device file in my "/dev" directory,
is that the root cause?

On Mon, Aug 20, 2012 at 11:47 PM, Stefano Stabellini <
[e-mail]> wrote:
> On Mon, 20 Aug 2012, Konrad Rzeszutek Wilk wrote:
> > On Mon, Aug 20, 2012 at 09:39:56PM +0800, Wei Xu wrote:
> > > > Hi All,
> > > > I'm try to set up and verify Xen console driver base on Fedora 17
>
> and Xen
> > > > 4.1.2 with hvm guest mode,
> > > > i searched around and got a link, it give steps both for PV and HVM
>
> mode,
> > > > I followed the HVM guide
> > > > and upgraded my kernel to 3.5.0.
> > > >        http://www.dedoimedo.com/computers/xen-console.html
> > > >
> > > > After that, I can got console output with "xm console <dom_id>", but
>
> the
> > > > console driver is not used when I tracing the driver
> >
> > .. I am not sure I understand: "when I tracing the driver" ? Are
> > you referring to the PV driver?
> > > > with "crash" utility, by examing the "console_drivers", the console
>
> driver
> > > > is still "serial8250 console", so i wonder if I didn't
> > > > set up it properly or something else, is there someone ever
>
> experienced
> > > > it, thanks.
> >
> > Hm, it should be the hvc one. Perhaps Stefano knows..
> >
> > CC-ing him and xen-devel here.
>
> An HVM guest has access to both an emulated serial (if a serial="pty"
> parameter is present in the VM config file) and a PV console.
> However the default first console is the emulated serial with libxl (see
> libxl__primary_console_find), that is what you get when you execute "xl
> console" without -t.
>
> But if you edit inittab to spawn a getty on hvc0 and then execute "xl
> console -t pv" you should get access to the PV console.

[Stefano Stabellini]

On Thu, 23 Aug 2012, Wei Xu wrote:
> Thanks for your reply.
>
> I have tried the method but it looks still can't work, there is no "hvc0" device file in my "/dev" directory,
> is that the root cause?

Reading again the previous message, it is clear that you are still using
xm/xend as toolstack to create VMs. Unfortunately xend doesn't support
PV consoles for HVM guests, you need to use the new xl toolstack if
you'd like to use that functionality.

See: http://wiki.xen.org/wiki/XL

[Wei Xu]

Thanks，i'll try it

On Thursday, August 23, 2012, Stefano Stabellini wrote:
> On Thu, 23 Aug 2012, Wei Xu wrote:
> > Thanks for your reply.
> >
> > I have tried the method but it looks still can't work, there is no
>
> "hvc0" device file in my "/dev" directory,
> > is that the root cause?
>
> Reading again the previous message, it is clear that you are still using
> xm/xend as toolstack to create VMs. Unfortunately xend doesn't support
> PV consoles for HVM guests, you need to use the new xl toolstack if
> you'd like to use that functionality.
>
> See: http://wiki.xen.org/wiki/XL

[Wei Xu]

Thanks，i'll try it

On Thursday, August 23, 2012, Stefano Stabellini wrote:
> On Thu, 23 Aug 2012, Wei Xu wrote:
> > Thanks for your reply.
> >
> > I have tried the method but it looks still can't work, there is no
>
> "hvc0" device file in my "/dev" directory,
> > is that the root cause?
>
> Reading again the previous message, it is clear that you are still using
> xm/xend as toolstack to create VMs. Unfortunately xend doesn't support
> PV consoles for HVM guests, you need to use the new xl toolstack if
> you'd like to use that functionality.
>
> See: http://wiki.xen.org/wiki/XL