* Russell King - ARM Linux <linux@xxxxxxxxxxxxxxxx> [110117 11:20]: > This patch series reworks the ARMv6/ARMv6K support options, code > selection, and bit operations such that it's possible to safely > build a kernel which supports ARMv6, ARMv6K, ARMv7 and ARMv7 SMP > in one image. > > Currently, we use CPU_V6 for both ARMv6 and ARMv6K, setting CPU_32v6K > if we have the K extensions. CPU_32v6K directly controlled whether > we should include the ARMv6K instructions (clrex, load/store exclusive > byte, half-word, double). As the bitops code uses the load/store > exclusive byte operations, unsetting CPU_32v6K results in these > falling back to their non-SMP local-irq-disabling variants. These > are only safe in uniprocessor environments. > > So, the first two patches convert the bitops to use the ARMv6 load/store > exclusive word operations - and ensuring correctness by ensuring that > the pointer passed in is word-aligned. > > We then introduce a new CPU_V6K which indicates that we're including > an ARMv6K CPU in the build, which frees up CPU_V6 to mean that we're > including an ARMv6 non-K CPU. > > We can then use CPU_V6 to ensure that the non-v6K code paths which are > still SMP safe are selected. > > Without this patch set, such a kernel will be unsafe when run on > SMP platforms as it omits necessary SMP code to ensure that bit > operations are safe. Amazing, based on a quick test this series boots just fine on non-v6K omap2420 using omap2plus_defconfig :) Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
