Re: [Xen-devel] [PATCH] xen: remove CONFIG_XEN_DOM0 compile option

[Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>]

On Fri, 6 Jan 2012, Andrew Jones wrote:
> XEN_DOM0 is a silent option that has been automatically selected when
> CONFIG_XEN is selected since 6b0661a5e6fbf. If this option was changed
> to a menu configurable option then it would only give users the ability
> to compile out about 100 kbytes of code.

I think that it is less than that because backends are not tied to dom0
in any way, even though currently they cannot be compiled without
XEN_DOM0.
Running a network or block backend in domU is a well known
configuration.
Therefore the code compiled out only amounts to about 10K.


> diff --git a/drivers/xen/Kconfig b/drivers/xen/Kconfig
> index 8795480..0725228 100644
> --- a/drivers/xen/Kconfig
> +++ b/drivers/xen/Kconfig
> @@ -78,8 +78,9 @@ config XEN_DEV_EVTCHN
>  
>  config XEN_BACKEND
>       bool "Backend driver support"
> -     depends on XEN_DOM0
>       default y
> +     depends on XEN && PCI_XEN && SWIOTLB_XEN
> +     depends on X86_LOCAL_APIC && X86_IO_APIC && ACPI && PCI
>       help
>         Support for backend device drivers that provide I/O services
>         to other virtual machines.

I think we can trimmer the dependency list here: after all backends can
be run in unpriviledged guests as well (see driver domains).
So I think it should depend only on XEN.

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