On 07.02.2013 23:07, Thierry Reding wrote: > On Wed, Feb 06, 2013 at 01:23:17PM -0800, Terje Bergström wrote: >>>> That's the security firewall. It walks through each submit, and ensures >>>> that each register write that writes an address, goes through the host1x >>>> reloc mechanism. This way user space cannot ask 2D to write to arbitrary >>>> memory locations. >>> I see. Can this be made more generic? Perhaps adding a table of valid >>> registers to the device and use a generic function to iterate over that >>> instead of having to provide the same function for each client. >> For which one does gcc generate more efficient code? I've thought a >> switch-case statement might get compiled into something more efficient >> than a table lookup. >> But the rest of the code is generic - just the one function which >> compares against known address registers is specific to 2D. > Table lookup should be pretty fast. I wouldn't worry too much about > performance at this stage, though. Readability is more important in my > opinion. A lookup table is a lot more readable and reusable I think. If > it turns out that using a function is actually faster we can always > optimize later. You're right about performance. We already saw quite a bad performance hit with the current firewall, so we'll need to worry about performance later. I'll take a look at converting the register list to a table. Instead of always doing a linear search of a table, a bitfield might be more appropriate. Terje _______________________________________________ dri-devel mailing list dri-devel@xxxxxxxxxxxxxxxxxxxxx http://lists.freedesktop.org/mailman/listinfo/dri-devel
