Re: [Xen-devel] [PATCH 3/4] xen kconfig: add dom0 support help text

On Fri, 6 Jan 2012, Andrew Jones wrote:

quoted

Almost all of the things which dom0 needs (e.g. PCI device management
etc) is also required by a domU with passthrough enabled so the
savings
are really very slight.

We are talking less than 1k of code AFAICT, 319 bytes for
arch/x86/xen/vga.o and 573 for drivers/xen/xenfs/xenstored.o plus
whatever xen_register_gsi (a couple of dozen lines of code) adds to
arch/x86/pci/xen.o. grep doesn't show CONFIG_XEN_DOM0 being used
anywhere else. What savings do you see in practice from disabling
just
this symbol?

I completely agree that the saving are near none. The savings, however,
aren't the only reason to drive the change. It's actually the symbol
name itself. Unfortunately configs can be perceived as a contract of
support, i.e. if feature xyz is enabled in the distro's config, then
the distributor must have selected, and therefore will support, said
feature.

I didn't make this motivation clear in my initial post, because I was
hoping to spare people some eye rolling.

I thought that in the kernel community we make decisions based on
technical merits rather than "contracts of support". 
Given that disabling the symbol saves near to nothing, the logical thing
to do is removing the symbol altogether.