RE: [Xen-users] Linux HVM tutorial ?

["Petersson, Mats" <Mats.Petersson@xxxxxxx>]

> -----Original Message-----
> From: xen-users-bounces@xxxxxxxxxxxxxxxxxxx 
> [mailto:xen-users-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Tim Post
> Sent: 23 November 2006 16:12
> To: Gerd Hoffmann
> Cc: Petersson, Mats; xen-users@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Xen-users] Linux HVM tutorial ?
> 
> On Thu, 2006-11-23 at 16:59 +0100, Gerd Hoffmann wrote:
> 
> > Just does what it says, redirect serial port to the console.
> 
> I figured as such, but since the commented pointed at 
> /dev/pts I thought
> it best to ask.
> 
> 
> > So you can setup a getty at /dev/ttyS0, and/or boot your 
> linux kernel
> > with "console=ttyS0", then use "xm console <domain>" to 
> connect to the
> > other end of the virtual serial line and see the messages, 
> log into the
> > machine, ...
> > 
> 
> Should arguments to the kernel to be fully virtualized be specified
> here:
> 
> kernel = "/usr/lib/xen/boot/hvmloader"
> 
> i.e.
> 
> /usr/lib/xen/boot/hvmloader console=ttys0 [ ... ]

No, that won't work - hvmloader doesn't take ANY arguments [grep main
hvmloader.c returns "main(void)"].

More information than you need to know right now: 
All hvmloader does is to load the BIOS, VGA/CIRRUS BIOS, ACPI tables and
run a little bit of code that is essentially "reset the processor"
(which means, reset a bunch of registers to x86 standard reset values
and jump to 0xF000:0xFFF0 - it is slightly different between VMX and SVM
- but the effect is the same). 

More comments on serial output from HVM domains:
I don't know if there's any way to redirect the early "start of day"
output to a serial line instead of the SDL/VNC VGA output - it wouldn't
be very hard to write a bit of code to just send everything that goes to
text-mode VGA to serial port, except for those applications that don't
output things in order (i.e. write something at mid-screen level, then
write at the top, or some such). 

For later stage output, you'll be using the grub (or whatever
boot-loader you use) to give kernel parameters, and a that stage, there
are lots of settings available for you... 

--
Mats



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