RE: [Xen-users] [SEMI-SOLVED] XenSerialConsole help + GRUB2 (Machine locks up on boot)

[Mike Viau <viaum@xxxxxxxxxxxxxxx>]

 > Mon, 12 Apr 2010 19:02:12 +0300 <pasik@xxxxxx> wrote:
>
> On Mon, Apr 12, 2010 at 11:55:49AM -0400, Mike Viau wrote:
> > > >
> > > > > Can you please paste the full boot messages before it locks up?
> > > > >
> > > > >
> > > >
> > > > Unfortunately no, because I am not getting any output (kernel
> > messages) to
> > > > the terminal on the other machine listening. I attached a photo of
> > what I
> > > > see on the screen when console=com1,vga.
> > > >
> > >
> > > So do you see the Xen hypervisor boot messages at least?
> > >
> > >
> >
> > Nothing in fact.
> >
>
> Please paste your grub.conf again.
>
>

Attached is grub.cfg.

Please notice:

menuentry "Xen 4.0.0 / PVOPS 2.6.32-4-xen-amd64 with a serial console" {
insmod ext2
set root=(hd2,1)
search --fs-uuid --set 13f83e98-6e2e-48a5-992e-b266d17bbfd3
multiboot /xen.gz dom0_mem=2048M loglvl=all guest_loglvl=all sync_console console_to_ring com1=115200,8n1,0x1000,0 console=com1
module /vmlinuz-2.6.32-4-xen-amd64 root=UUID=a8129b5a-f8cc-460e-bda4-93cc547b9f7e ro console=hvc0 earlyprintk=xen
module /initrd.img-2.6.32-4-xen-amd64
}
 

I have tried using both 0x1000 and 0x1008 with IRQ 21 and 22 and 0

> > > > > > Motherboard:
> > > > > >
> > > >
> > [4]http://www.intel.com/products/desktop/motherboards/DP55WG/DP55WG-overview.htm
> > > > > > [5]http://ark.intel.com/Product.aspx?id=40078
> > > > > >
> > > > > > Add-in serial card:
> > > > > > "Cables Unlimited IOC-2200 2-Port DB9 Serial PCI I/O Card"
> > > > > >
> > > >
> > [6](http://www.tigerdirect.ca/applications/SearchTools/item-details.asp?EdpNo=1431863&CatId=1422)
> > > > > >
> > > > >
> > > > > Does the serial console work with plain baremetal Linux? (without
> > Xen).
> > > > >
> > > > >
> > > >
> > > > No it does not. I started a thread over on the Debian mailing-list for
> > > > this though to see if anyone there had any ideas. I have got no
> > replies as
> > > > of yet.
> > > >
> > > > Mainly I was asking if one needed to build the mcs9865-serial.ko
> > (kernel
> > > > module) against the kernel source for the running kernel in order to
> > log
> > > > kernel message during boot time or does grub implement a generic
> > driver to
> > > > capture the kernel message?
> > > >
> > >
> > > Uhm.. are you saying this serial-card requires some non-standard driver?
> > > Then it probably can't be used as a serial console.
> > >
> >
> > I was hoping this was not the case. The Linux kernel includes drivers for
> > serial port devices does it not? Can anyone confirm if the Moschip MCS9865
> > is or is not supported by the Linux kernel?
> >
> > Can I try using a generic driver with this card that is already built into
> > the Linux kernel?
>
> Yeah, sure, try it.

What driver (name or module name) do you suggest I start with. Another system has drivers like:

8250_accent.ko         8250_exar_st16c554.ko  8250_hub6.ko           jsm/                   serial_cs.ko          
8250_boca.ko           8250_fourport.ko       8250_mca.ko            max3100.ko

What about serial_cs.ko?

http://www.google.com/#hl=en&source=hp&q=serial_cs.ko&meta=&aq=f&aqi=&aql=&oq=&gs_rfai=&fp=6909149b0ecd8aa

> I don't know more about the serial card you have.
>
> > > The PCI serial-card needs to show up as a 'real' serial port, so that
> > > Xen can output there boot time (before any drivers are loaded in dom0
> > kernel).
> > >
> >
> > How does one determine if it is real serial port or not. No /dev/ttyS[?]
> > devices are created in the filesystem and there is nothing in the dmesg
> > out for these serial ports either. The PCI add-in card was advertised to
> > be Linux compatible.
> >
>
> Real serial ports are available without any drivers, at boot time before Linux is loaded.
> Xen needs to log to the serial port before _any_ drivers are loaded, even before dom0 Linux is loaded.
>

So the serial line use by grub 'taps' into real serial ports only right? So is a driver even needed at all if all the details such as I/O address, IRQ, speed, etc are provided in the grub configuration?

Many there is a hardware limitation I am unaware or blind to see?

> It's the same with USB-serial-adapters.. you can't use those for serial console
> because they don't work before the driver is loaded.
>
> But yeah.. good luck!
>
> -- Pasi
>


As the subject says "semi-solved."

Used the patch found here:

http://marc.info/?l=linux-serial&m=124975806304760

8250_pci: add support for MCS9865

So lesson learned Pasi, a kernel driver must be compiled with the running kernel in order to capture boot messages from it. The driver does not load from the bootloader or from grub itself.

-M

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