compatible method of handling floating point exceptions.
Make kernel support for teh fpu non-optional (486SX should still work).
Only 386 cpus support external fpu, and i386 support was removed years ago.
This means that the npx code no longer uses port 0xf0 or interupt 13.
All the "npx at isa" lines go from the configs, arch/i386/isa/npx.c
is now mandatory for all i386 kernels.
I've renamed npxinit() to fpuinit() and npxinit_cpu() to fpuinit_cpu()
to match the very similar amd64 functions.
The fpu of the boot cpu is now initialised by a direct call from
cpu_configure(), this enables FP emulation for a 486SX.
(for amd64 the cr0 values are set in locore.S and similar).
This fixes a long-standing bug in linux_setregs() - which did not
save the fpu regsiters if they were active.
I've test booted a single cpu i386 kernel (using anita).
amd64 builds - none of teh changes should affect it.
The i386 XEN kernels build, but I'm not sure where they set cr0, and
it might have got lost!
- Fix a bug that the puc cn mechanism doesn't use the UART's frequency
in pucdata.c's table.
- Add a new option PUC_CNAUTO. If this option is set, consinit() in
x86/x86/consinit.c checks puc com device to use it as console.
Without this option, the behavior is the same as before.
- Add a new config parameter PUC_CNBUS. The old code scans bus #0 only.
If PUC_CNBUS is set, the specified number's bus will be scanned.
- Rename comcnprobe() to puc_cnprobe() to make it clear.
- Rename comcninit() to puc_cninit() to make it clear.
- Add code for a device that a device's com register is MMIO (#if0 ed).
abridged versions.
The code in xmm_to_s87_tag() looked at the wrong register when trying
to generate 0b01 (zero) and 0b10 (NaN etc) because the registers are
relative to the stack top, but the tag words are absolute.
Since even a real 387 generates the correct tag values when the tag word
(or register value) is loaded there is no point generating other than
0b00 (used) and 0b11 (unused).
The compiler also made a pig's breakfast of the register copy loop.
When convering from fsave to (the larger) fxsave format don't bother
copying the fp register values if none are in use.
Converting the other way we do copy them all because the target buffer
is often written to userspace (and has no padding).
i386 core dumps still seem ok - and do use this code.
