On Mon, Jan 30, 2023 at 03:46:32PM +0800, Andy Chiu wrote: > On Thu, Jan 26, 2023 at 5:04 AM Conor Dooley <conor@xxxxxxxxxx> wrote: > > Firstly, no-implicit-float is a CFLAG, so why add it to march? > I placed it in march because I thought we need the flag in vdso. And, > KBUILD_CFLAGS is not enough for vdso. However, I think we don't need > this flag in vdso since it is run in user space anyway. > > There is an existing patch on the list for enabling this flag, but I > > recall Palmer saying that it was not actually needed? > The flag is needed for clang builds to prevent auto-vectorization from > using V in the kernel code [1]. > > > Palmer, do you remember why that was? > The discussion[2] suggested that we need this flag, IIUC. But somehow > the patch did make it into the tree. I know, in [1] I left an R-b as the patch seemed reasonable to me. Palmer mentioned some reason for not thinking it was actually needed but not on-list, so I was hoping he'd comment! And I suppose, it never got any further attention as it isn't needed by any in-tree code? > [1]https://lore.kernel.org/all/CAOnJCULtT-y9vo6YhW7bW9XyKRdod-hvFfr02jHVamR_LcsKdA@xxxxxxxxxxxxxx/ > [2]https://lore.kernel.org/all/20221216185012.2342675-1-abdulras@xxxxxxxxxx/
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