On 3/5/25 01:07, Ingo Molnar wrote:>> Alternatives considered: >> - Make kernel-mode FPU sections fully preemptible. This would require >> growing task_struct by another struct fpstate which is more than 2K. > > So that's something that will probably happen once the kernel is built > using APX anyway? I was expecting that building the kernel with APX would be very different than a kernel_fpu_begin(). We don't just need *one* more save area for APX registers: we need a stack, just like normal GPRs. We'd effectively need to enlarge pt_regs and fix up things like PUSH_AND_CLEAR_REGS to save the APX registers in addition to the good old GPRs before calling C code. That's what I was thinking at least. Did folks have more clever ideas?
