Re: Xen 4.18 doesn't display on an iDRAC-6 console, and NetBSD console=pc locks up early in boot

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Sun, Jan 07, 2024 at 02:07:51PM -0800, Greg A. Woods wrote:
> [[ Resending this without the image attachment.... ]]
> 
> So I've got this remote Xen server, a Dell R510, that I manage and I
> only have iDRAC-6 access to its "vga" console.
> 
> My recent upgrade to 4.18 (from 4.13) revealed some problems:
> 
> 1. Xen does not display anything on the console.

I've set up Xen on a newer system and didn't have issue with the VGA
console. In by case it was a UEFI setup though.
Are you using UEFI or legacy BIOS ?

Did you try playing with the various vga= options to Xen ?

> 
> 2. NetBSD XEN3_DOM0 (in this case a somewhat older -current) when
>    running under 4.18 locks up early in the boot of the dom0.  (see
>    attached image) (same kernel boots find with console=pc under 4.13)
> 
> However I found that if I told/allowed NetBSD XEN3_DOM0 to use
> xencons(4) then it boots "silently" and quite quickly and all is well,
> except of course for anyone expecting to use the actual console for
> anything, e.g. single-user mode, is screwed.  Not the end of the world
> though if one has a GENERIC kernel also available.  Not that it would
> be of any use, but too bad Xen won't allow "xl console Domain-0".

With vga=keep Xen would then display the dom0's kernel message, but you
can't input anything to the dom0's kernel.

> 
> Furthermore the XEN3_DOM0 kernel doesn't see a com0 on this machine with
> the current working boot (only a com1), so "console=com0" is effectively
> the same as console=xencons as the latter is what's attached anyway.
> GENERIC does see both com0 and com1 though, so the hardware is there:
> 
> 	com0 at isa0 port 0x3f8-0x3ff irq 4: ns16550a, working fifo
> 	com1 at isa0 port 0x2f8-0x2ff irq 3: ns16550a, working fifo
> 
> I'm guessing that with "/xen console=com1,vga" that the hypervisor hides
> the com0 from the dom0.

yes, that's it. But you should see the Xen boot messages on com0 then
(and the dom0's boot messages with comsole=xencons)

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--