On Tue, Jun 23, 2020 at 01:03:18PM +0200, Patrick Wildt wrote: > On Tue, Jun 23, 2020 at 06:51:20AM -0400, Bryan Steele wrote: > > On Mon, Jun 22, 2020 at 11:10:10PM -0700, jo...@armadilloaerospace.com > > wrote: > > > Are SSE instructions allowed in the AMD64 kernel? Is #ifdef __SSE__ > > > a sufficient guard? > > > > > > I have a rasops32 putchar with SSE that is 2x faster. > > > > No, in general you cannot using FP instructions in the kernel, also the > > kernel is often compiled with -msoft-float on platforms that support it. > > Exceptions are being made for amdgpu drm, where some of the files are > compiled with sse enabled, though the code is guarded with > fpu_kernel_enter(). DC_FP_START() and DC_FP_END() to be precise, which > are macros pointing to the kernel functions.
^ patrick got there first. :-)
