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It does... and doing a quick search of the kernel source it's not actually used for anything I can't find it referenced outside of itself. There is FPU emulatio
by leeter 5y ago
It does... and doing a quick search of the kernel source it's not actually used for anything I can't find it referenced outside of itself. There is FPU emulation for m68K that is, but x87 is not.
- cesarb 5y ago> and doing a quick search of the kernel source it's not actually used for anything I can't find it referenced outside of itself. It's being used here: https://lxr.missinglinkelectronics.com/linux+v5.16/arch/x86/kernel/traps.c#L1187 https://lxr.missinglinkelectronics.com/linux+v5.16/arch/x86/... Whenever the kernel gets a "device not available" exception, and CONFIG_MATH_EMULATION is set (which is the case when the kernel is compiled for a 486SX), and the CPU does not have a real FPU, and the "emulation" flag on CR0 is set, it calls the FPU emulator.
- leeter 5y agoGood to know I was looking in the wrong spot, I was looking for what looked like the most likely header other parts of the code would be using.
- amluto 5y agoAh, you got faked out. The kernel doesn’t really use FPU even in modern CPUs. The emulation is for userspace’s benefit, not the kernel’s