* Russell King - ARM Linux <[email protected]> [100322 17:12]: > On Fri, Mar 19, 2010 at 08:58:05AM -0700, Tony Lindgren wrote: > > * Russell King - ARM Linux <[email protected]> [100319 01:49]: > > > On Thu, Mar 18, 2010 at 06:35:21PM -0700, Tony Lindgren wrote: > > > > -#if defined(CONFIG_HAS_TLS_REG) > > > > - mcr p15, 0, r3, c13, c0, 3 @ set TLS register > > > > -#elif !defined(CONFIG_TLS_REG_EMUL) > > > > - mov r4, #0xffff0fff > > > > - str r3, [r4, #-15] @ TLS val at 0xffff0ff0 > > > > +#if !defined(CONFIG_TLS_REG_EMUL) > > > > + ldr r4, =elf_hwcap > > > > + ldr r4, [r4, #0] > > > > + tst r4, #HWCAP_TLS @ hardware with TLS? > > > > > > This is really really inefficient. Both the second ldr and tst will stall > > > the pipeline because they need to wait for the result of the precending > > > ldr. Can we do better by re-ordering some instructions? > > > > Or set ifdef CONFIG_CPU_V6 and test for the cp15 id register every time.. > > I was suggesting that it might be worth trying to reorder the instructions > here so that we're not immediately using the result of the ldr in the > next instruction. We have plenty of registers available here (everything > except r0-r2, r6, fp.)
Yeah sure, I'll take a look. I'll repost an updated version after I get a chance to play with this again. Might be a little while before I get back to this, but this would be for the next merge window anyways. > > > Also, the ifndef seems incorrect - if we have TLS_REG_EMUL we seem to omit > > > all this code. > > > > Is the current ifdef elif wrong? The current code does not seem to > > do anything if TLS_REG_EMUL is set and HAS_TLS_REG is not set. > > HAS_TLS_REG depends !TLS_REG_EMUL. > > Now I look back, I don't think so. Ignore that comment. OK Regards, Tony -- To unsubscribe from this list: send the line "unsubscribe linux-omap" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html
