linux-kernel - Re: [PATCH] xen: use hvc console for dom0

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Message-ID: <16e21e9e-35d5-81f2-0f90-df5f8ac72446@oracle.com>
Date:   Mon, 26 Feb 2018 14:02:17 -0500
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     jbeulich@...e.com
Subject: Re: [PATCH] xen: use hvc console for dom0

On 02/26/2018 06:08 AM, Juergen Gross wrote:
> Today the hvc console is added as a preferred console for pv domUs
> only. As this requires a boot parameter for getting dom0 messages per
> default add it for dom0, too.
>
> Signed-off-by: Juergen Gross <jgross@...e.com>
> ---
>  arch/x86/xen/enlighten_pv.c | 4 +++-
>  1 file changed, 3 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/xen/enlighten_pv.c b/arch/x86/xen/enlighten_pv.c
> index c047f42552e1..d27740a80c5e 100644
> --- a/arch/x86/xen/enlighten_pv.c
> +++ b/arch/x86/xen/enlighten_pv.c
> @@ -1377,7 +1377,6 @@ asmlinkage __visible void __init xen_start_kernel(void)
>  	if (!xen_initial_domain()) {
>  		add_preferred_console("xenboot", 0, NULL);
>  		add_preferred_console("tty", 0, NULL);
> -		add_preferred_console("hvc", 0, NULL);
>  		if (pci_xen)
>  			x86_init.pci.arch_init = pci_xen_init;
>  	} else {
> @@ -1410,6 +1409,9 @@ asmlinkage __visible void __init xen_start_kernel(void)
>  
>  		xen_boot_params_init_edd();
>  	}
> +
> +	add_preferred_console("hvc", 0, NULL);
> +

Won't this prevent dom0 output from showing up on vga console by default?

-boris

>  #ifdef CONFIG_PCI
>  	/* PCI BIOS service won't work from a PV guest. */
>  	pci_probe &= ~PCI_PROBE_BIOS;