Re: [PATCH 5 of 6] unplug emulated devices

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

On Thu, Apr 22, 2010 at 04:16:50PM +0100, Stefano Stabellini wrote:
> Hi all,
> this patch adds a xen_unplug command line option to the kernel to unplug
> xen emulated devices.

For those folks who don't understand the pain^H^H^Htransition from emulated device
to a PV device, can you do a more detailed writeup?

Why don't we want this be enabled by default? Perhaps you want to make
the parameter only parse the disable option - devices which we _dont_
want to be unplugged. So paramter name would 'xen_keep_plugged='.
> 
> Signed-off-by: Stefano Stabellini <stefano.stabellini@eu.citrix.com>
> 
> ---
>  arch/x86/xen/enlighten.c |   30 +++++++++++++++++++++++++++++-
>  1 files changed, 29 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
> index 2ce2da1..7acb130 100644
> --- a/arch/x86/xen/enlighten.c
> +++ b/arch/x86/xen/enlighten.c
> @@ -37,6 +37,7 @@
>  #include <xen/interface/memory.h>
>  #include <xen/interface/hvm/hvm_op.h>
>  #include <xen/interface/hvm/params.h>
> +#include <xen/interface/platform_pci.h>
>  #include <xen/features.h>
>  #include <xen/page.h>
>  #include <xen/hvm.h>
> @@ -86,6 +87,7 @@ struct shared_info xen_dummy_shared_info;
>  void *xen_initial_gdt;
>  
>  int xen_have_vector_callback;
> +int unplug;
>  
>  /*
>   * Point at some empty memory to start with. We map the real shared_info
> @@ -1389,9 +1391,35 @@ void __init xen_guest_init(void)
>  		x86_platform_ipi_callback = do_hvm_pv_evtchn_intr;
>  		xen_have_vector_callback = 1;
>  	}
> -
> +	if (unplug) {
> +		/* unplug emulated devices */
> +		outw(UNPLUG_ALL, XEN_IOPORT_UNPLUG);
> +	}
>  	have_vcpu_info_placement = 0;
>  	x86_init.irqs.intr_init = xen_init_IRQ;
>  	machine_ops = xen_machine_ops;
>  }
>  
> +static int __init parse_unplug(char *arg)
> +{
> +	char *p, *q;
> +
> +	for (p = arg; p; p = q) {
> +		q = strchr(arg, ',');
> +		if (q)
> +			*q++ = '\0';
> +		if (!strcmp(p, "all"))
> +			unplug |= UNPLUG_ALL;
> +		else if (!strcmp(p, "ide-disks"))
> +			unplug |= UNPLUG_ALL_IDE_DISKS;
> +		else if (!strcmp(p, "aux-ide-disks"))
> +			unplug |= UNPLUG_AUX_IDE_DISKS;
> +		else if (!strcmp(p, "nics"))
> +			unplug |= UNPLUG_ALL_NICS;
> +		else
> +			printk(KERN_WARNING "unrecognised option '%s' "
> +				 "in module parameter 'dev_unplug'\n", p);
> +	}
> +	return 0;
> +}
> +early_param("xen_unplug", parse_unplug);
> -- 
> 1.5.4.3
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xensource.com
> http://lists.xensource.com/xen-devel