On Fri, 2011-01-28 at 09:59 +0000, Russell King - ARM Linux wrote: > On Fri, Jan 28, 2011 at 09:46:06AM +0000, Catalin Marinas wrote: > > My point is that we may want SWP_EMULATE disabled (or depending on ! > > CPU_USE_DOMAINS). With domains enabled every read-only user page is > > writeable by the kernel. This has the side-effect that SWP emulation > > using LDREX/STREX breaks COW. > > Yes, and maybe we should instead just enable the SWP instruction by default > on ARMv7, and if SWP emulation is built, disable it at that point.
We can't disable the SWP instruction as long as domains are enabled (COW not working for in-kernel STREX). On ARMv7 we could always force R/O kernel/user pages in set_pte_ext independent of the domains setting and have early_trap_init() use vectors_page() if cpu_architecture() >= 7 (this would actually catch ARM11MPCore as well because of the way we interpret CPUID). -- Catalin -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
