On Tue, Nov 30, 2010 at 10:05:50PM +0000, Russell King - ARM Linux wrote: > On Tue, Nov 30, 2010 at 10:48:34AM -0800, Greg KH wrote: > > On Tue, Nov 30, 2010 at 06:40:49PM +0000, Russell King - ARM Linux wrote: > > > There's lots of static devices, not only platform devices, in the ARM > > > tree. It's going to be a hell of a lot of work to fix this all up > > > properly. > > > > I agree, it's been abused for many years this way :( > > I don't agree that it is abuse - it was something explicitly allowed by > the original device model design by Patrick, with the condition that > such a device was never unregistered. That's exactly the way we treat > these devices. I understand Pat allowed this, I just don't agree that it's the correct thing to do :) -mm had a patch for a long time that would throw up warnings if you ever did this for x86 so that arch should be clean of this issue by now. > What I'm slightly concerned about is that this is going to needlessly > bloat the kernel - we're going to have to find some other way to store > this information, and create devices from that - which means additional > code to do the creation, and data structures for it to create these from. > There will be additional wastage from kmalloc as kmalloc doesn't allocate > just the size you ask for, but normally a power of two which will contain > the size. > > That could potentially mean that as the device structure is 216 bytes, > kmalloc will use the 256 byte allocation size, which means a wastage of > 40 bytes per device structure. On top of that goes the size of > resources with the allocation slop on top for that, and then there's > another allocation for the platform data. > > Has anyone considered these implications before making this choice? Yes, I have, which is one reason I haven't done this type of change yet. I need to figure out a way to not drasticly increase the size and still make it easy and simple for the platform and driver write their code. It's a work in progress, but wherever possible, I encourage people to not make 'struct device' static. thanks, greg k-h _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
