Re: Xen 4 serial hangs during boot

[Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>]

On Thu, Jul 26, 2012 at 03:10:25PM +0100, Jan Beulich wrote:
> >>> On 26.07.12 at 15:50, Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> wrote:
> > Then recently (yesterday?) the upstream kernel started doing something
> > wonky on this card:
> > 
> > 01:05.0 Serial controller: NetMos Technology PCI 9835 Multi-I/O Controller 
> > (rev 01)
> > Under Xen, when it boots it hits right here:
> > [    1.240774] pci 0000:01:05.0: [9710:9835] type 00 class 0x070002
> > and then stops [note: I hadn't really done any investigation to see
> > if the machine is dead or if it continues on, but with the serial port just
> > wedged hard].
> 
> The machine state here, if accessible at all, would of course be
> very interesting.

<nods> Hope to get to that today.
> 
> > On baremetal it can actually read the IO bars:
> > [    1.240774] pci 0000:01:05.0: [9710:9835] type 00 class 0x070002
> > [    1.247075] pci 0000:01:05.0: reg 10: [io  0xe050-0xe057]
> > [    1.252734] pci 0000:01:05.0: reg 14: [io  0xe040-0xe047]
> > [    1.258394] pci 0000:01:05.0: reg 18: [io  0xe030-0xe037]
> > [    1.264054] pci 0000:01:05.0: reg 1c: [io  0xe020-0xe027]
> > [    1.269713] pci 0000:01:05.0: reg 20: [io  0xe010-0xe017]
> > [    1.275372] pci 0000:01:05.0: reg 24: [io  0xe000-0xe00f]
> > 
> > so I am wondering if the back-ports in Xen 4.1 for dealing with
> > PCI have something to do with this? 
> 
> What backports are you thinking of? I just went through the titles
> of everything since 4.1.2, and nothing that has "PCI" in it looks
> in any way dangerous.

I know :-( That is why I am thinking it might be the kernel, but when
I did a git bisection I got an innocious Documentation patch. But then
recently (say 3.5) has been doing some weird stuff in the PCI space

(like it seems to have MSI's and BARs disabled - at least when using
them with xen-pciback to hide them). 
> 
> Jan