3 ms·
We have robust support for alternate code paths based on CPU flags after many years of this kind of thing. Is that really necessary or useful? Custom microcode
by ip26 8y ago
We have robust support for alternate code paths based on CPU flags after many years of this kind of thing. Is that really necessary or useful?
Custom microcode handling is a lot more brittle and chip- specific yet nearly equivalent to overloading in software your call to some avx512 op.
- raverbashing 8y agoYou're right, it isn't needed The "last time" this was done was in the x87 days, where if the math coprocessor wasn't installed you could trap the corresponding interrupt and handle it to emulate the instructions.
- bpye 8y agoThis is done for MIPS FP emulation too - https://www.linux-mips.org/wiki/Floating_point#The_Linux_kernel_and_floating_point https://www.linux-mips.org/wiki/Floating_point#The_Linux_ker...
- mschuster91 8y ago> The "last time" this was done was in the x87 days, where if the math coprocessor wasn't installed you could trap the corresponding interrupt and handle it to emulate the instructions. Wasn't Hackintosh (or getting new OS X running on too old hardware) also using this technology to "support" CPUs without the newest SSEx instruction sets?