ref: 24057fd4f494a00573d34adeaa7042721c1a06a0
parent: 04ce485f1b4453335db70b4a1b5d2c96458db3c1
author: cinap_lenrek <cinap_lenrek@felloff.net>
date: Sat Nov 4 16:08:22 EDT 2017
kernel: introduce per process FPU struct (PFPU) for more flexible machine specific fpu handling introducing the PFPU structue which allows the machine specific code some flexibility on how to handle the FPU process state. for example, in the pc and pc64 kernel, the FPsave structure is arround 512 bytes. with avx512, it could grow up to 2K. instead of embedding that into the Proc strucutre, it is more effective to allocate it on first use of the fpu, as most processes do not use simd or floating point in the first place. also, the FPsave structure has special 16 byte alignment constraint, which further favours dynamic allocation. this gets rid of the memmoves in pc/pc64 kernels for the aligment. there is also devproc, which is now checking if the fpsave area is actually valid before reading it, avoiding debuggers to see garbage data. the Notsave structure is gone now, as it was not used on any machine.