[Xen-users] RE: [Xen-devel] Run X in other domains?

[Sean Atkinson <sean@xxxxxxxxxxxxxx>]

( Replying to xen-users instead of old sourceforge list. )

On Mon, 2005-04-18 at 17:53 +0100, Ian Pratt wrote:
> > Initially I made some progress with the pre-built kernel 
> > binaries (from the current 2.0.5 release).  The xenU kernel 
> > lacks PCI support, and X reports "Cannot open /dev/tty0" 
> > using it in domain 1.  I switched to the xen0 kernel for PCI 
> > support, and then X reported "Cannot find a free VT".
> > 
> > The output from lspci lists everything but the VGA card in 
> > domain 0, unless "lspci -H 1" is used.  In other domains, 
> > lspci reports only the VGA card and "lspci -H 1" reports "You 
> > need to be root to have access to I/O ports".  However X 
> > still starts OK in domain 0, which surprised my.
> > I've confirmed that "xm dmesg" includes "Hiding PCI device 
> > 01:00.0 from DOM0" after passing "physdev_dom0_hide=01:00.1" to Xen.
> 
> I can see how you could start a very simple VGA-only Xserver -- by
> default dom0 happens to have access to the bottom 1MB of memory, which
> is enough to get a VGA Xserver working.

OK, I wasn't familiar with this.  However I've checked XFree86.0.log
from domain 0 for memory reports, and these two lines indicate more than
1MB is available, which may be a problem:

(II) SIS(0): Using 15808K of framebuffer memory
...
(II) SIS(0): VESA VBE Total Mem: 16384 kB

> > I've followed Ian's advice, rebuilding Linux 2.6.10 with the 
> > default xenU configuration eith XEN_PHSDEV_ACCESS added (to 
> > automatically enable
> > DUMMY_CONSOLE) plus PCI support.  However my kernel crashes 
> > immediately after "Freeing unused kernel memory", even when I 
> > pass "xencons=ttyS".
> > Perhaps the build broke somehow, or it's configuration is invalid?
> 
> I think you'll need to look through the oops message to see what's going
> on.

I've included a relevant section below - I could post the whole output
as a gzip attachment if it would help?

> You could try setting xencons=off just to rule xencons out.

The domain still exits, albeit silently without console output.  However
I have found that I need the suggested "xencons=ttyS" to avoid an
additional line of kernel output "Warning: unable to open an initial
console".

> I presume you've granted the PCI device to the other domain in it's
> config file? 

I hoped that the line "pci = [ '01,00,00' ]" in my previous post was
sufficient?

Cheers,

Sean.


Xen console output section from new domain:

Oops: 0000 [#1]
PREEMPT
Modules linked in:
CPU:    0
EIP:    0061:[<c0227a02>]    Not tainted VLI
EFLAGS: 00010246   (2.6.10xenU-mod)
EIP is at visual_init+0x72/0x1c0
eax: 00000000   ebx: c00e6e00   ecx: 00000000   edx: c00e6e00
esi: 00000000   edi: 00000001   ebp: 00000000   esp: c0023e94
ds: 007b   es: 007b   ss: 0069
Process init (pid: 1, threadinfo=c0022000 task=c03b69e0)
Stack: 00000000 000000d0 c00e6e00 00000000 c0227bf1 00000000 00000001
00000000
       c00c9bc0 00000000 00000000 c1365000 00400000 c022b1e8 00000000
ffffffed
       c00dab80 00000001 c021aa6d c1365000 c00dab80 c0023ef0 00000102
c1365000
Call Trace:
 [<c0227bf1>] vc_allocate+0xa1/0x1b0
 [<c022b1e8>] con_open+0x48/0xc0
 [<c021aa6d>] tty_open+0x24d/0x2d0
 [<c021a820>] tty_open+0x0/0x2d0
 [<c015e96a>] chrdev_open+0xea/0x1d0
 [<c0343324>] free_area_init_core+0xb4/0x300
 [<c0343324>] free_area_init_core+0xb4/0x300
 [<c015486a>] dentry_open+0x15a/0x240
 [<c0343324>] free_area_init_core+0xb4/0x300
 [<c0154708>] filp_open+0x68/0x70
 [<c0154989>] get_unused_fd+0x39/0xe0
 [<c0154af9>] sys_open+0x49/0x90
 [<c0109658>] syscall_call+0x7/0xb
Code: 40 6d 36 c0 a1 2c 6d 36 c0 89 42 28 8b 14 b5 80 7e 36 c0 85 d2 74
0a 8b 04 b5 40 6d 36 c0 89 50 28 8b 14 b5 40 6d 36 c0 8b 42 28 <8b> 18
85 db 74 35 89 1c 24 e8 80 8c f0 ff 85 c0 0f 84 09 01 00
 <0>Kernel panic - not syncing: Attempted to kill init!
 <0>Rebooting in 1 seconds..

-- 
Sean Atkinson <sean@xxxxxxxxxxxxxx>
Netproject


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