On Thu, Nov 16, 2017 at 08:17:31AM -0800, Sami Tolvanen wrote: > On Thu, Nov 16, 2017 at 11:58:11AM +0000, Will Deacon wrote: > > I'll be honest with you: I'm absolutely terrified about enabling this. > > That's understandable, I wouldn't want to enable this by default > quite yet either. This patch doesn't enable LTO for arm64, just makes > it possible to enable the feature. I'm perfectly fine with marking > CONFIG_LTO_CLANG experimental if it makes people more comfortable. > > > How much testing has this seen? > > I've been running clang LTO kernels for a few months on a Pixel 2 device > without any issues. This is on a 4.4 kernel though. > > > Right now, the C standard isn't on our side here and we're relying on > > the compiler not doing this kind of thing. Can we continue to rely on > > that in the face of LTO? > > I'll have to check with our LLVM experts, but I have not run into these > issues with current compiler versions. Looking at Andi's old patches, > looks like gcc might be more aggressive in reordering things with LTO > than clang. Ideally we'd get the toolchain people to commit to supporting the kernel memory model along side the C11 one. That would help a ton. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
