On Wed, Mar 31, 2010 at 02:57:20PM -0700, H. Peter Anvin wrote: > On 03/31/2010 02:54 PM, Russell King wrote: > > On Wed, Mar 31, 2010 at 04:42:25PM -0500, Christoph Lameter wrote: > >> Do not run the checks while we are in a single threaded context? > >> > >> I thought we had some dynamic code patching thingamy that could change > >> those when we go to smp mode? > > > > You have to remember that on embedded architectures, such as ARM, > > where XIP is supported we can't change the text segment at run time - > > which means dynamic code patching won't work. > > > > However, the kernel should still work in such situations. > > > > The question still remains what the incremental cost is of doing > irqsave/irqrestore. Compared to irq disable/enable, it wouldn't be much higher; saving can be done by a direct register to register move, so that should be relatively cheap. The restore may be a little bit more depending on the CPU arch version, but not significant. So there shouldn't be a problem from ARM POV to switch to using irqsave/irqrestore. -- Russell King Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/ maintainer of: -- To unsubscribe from this list: send the line "unsubscribe linux-arch" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
