Use of 'reserved' fields in var_screeninfo

[Kevin Hilman <khilman@mvista.com>]

Hello,

I've got a question about the purpose of the reserved fields in the
var_screeninfo struct:

struct fb_var_screeninfo {
	[ ... ]
	__u32 reserved[5];		/* Reserved for future compatibility */
};

What are these reserved for?  Is it appropriate for drivers to use these for
additional, HW-specific values that are then made available to the VSCREENINFO
ioctls?

If a driver does store state here, or attempt to pass info using an ioctl, the
data is promptly overwritten by fbcon during an fbcon_switch(), when it creates
a var_screeninfo struct, memsets it to zero, copies a couple fields and passes
it to fb_set_var().

I have a patch to copy the 'reserved' fields during an fbcon_switch() that
solves the problem but I'm not sure if this is the right thing to do.

-- 
Kevin Hilman
MontaVista Software -- http://www.mvista.com/



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