.arch i8086,jumps
+ .arch .287
.code16
.att_syntax prefix
.global __hard_irqrestore
.global __hard_ei
.global set_irq
+ .global cpu_detect
/* GCC glue */
.global __ashrsi3
* 1. We always make a syscall from user space
* 2. We never make a syscall with interrupts off
* 3. We treat the compiler scratch registers as fair game
+ *
+ * Useful to know: an interrupt pushes the words in this order
+ * flags, segment, ip
*/
unix_syscall_entry:
movb $1,kernel_flag
+ cld
+
sti
call unix_syscall
cli
xorb %ah,%ah
movw %ax,-4(%bp)
movw $23,-6(%bp)
- pushf
- /* FIXME: enable interrupts in mask */
- popw %ax
+ movw %ax,-8(%bp)
+ movw udata+U_DATA__U_PAGE,%ax
movw %ax,-10(%bp)
movw %cx,-12(%bp)
/* FIXME: need to fix MMU logic */
- movw udata+U_DATA__U_PAGE,%ax
- movw %ax,-14(%bp)
subw $-14,%bp
movw %es,%ax
movw %ax,%ds
movw %ax,%ss
movw %bp,%sp
/* To signal handler */
- iret
+ sti
+ retf
no_signal:
/*
* We effective return a 32bit ulong to gcc half of which is return
*/
doexec:
movw %sp,%bp
- movw 4(%bp),%ax
+ movw 2(%bp),%ax
cli
movb $0,kernel_flag
- /*
- * Stack the new CS:IP
- */
+
+ /* SS:SP to the user stack segment */
movw udata+U_DATA__U_PAGE2,%dx
- pushw %dx
- pushw %ax
- /*
- * Load the initial stack
- */
+ movw %dx, %ss
movw udata+U_DATA__U_ISP,%dx
movw %dx,%sp
- /* SS = DS */
+ /*
+ * Stack the new CS:IP
+ */
movw udata+U_DATA__U_PAGE,%dx
- movw %dx, %ss
+ pushw %dx /* CS: */
+ pushw %ax /* IP */
/*
* Load the data segment into ES
*/
* Just ES and DS left to go
*/
movb $0,udata+U_DATA__U_INSYS
+
/*
* And go
*/
sti /* will occur after the retf completes */
retf
-interrupt_handler:
- /* TODO */
- iret
-
trap_signal:
mov udata+U_DATA__U_PTAB, %ax
jmp ssig
sti
ret
-set_irq:
+set_irqvec:
pushw %bp
movw %sp,%bp
movw 4(%bp),%bx
movw %bp,%sp
ret
-
+/*
+ * Useful differences
+ * 8088/86 - cannot modify top 4 bits of flags, 80826 can
+ * 8088/8086/80186 - push sp is buggy and pushes the wrong value
+ * 8088/86 - word write to xx:FFFF wraps, 80186 doesn't wrap, 80286
+ * traps
+ *
+ * This lot needs to end up in discard
+ *
+ * Returns
+ * 0 8088/6
+ * 1 80C88/C86
+ * 2 NEC V20/30
+ * 3 186
+ * 4 286 or higher
+ *
+ * We don't bother trying to tell 186/188 and 86/89 bus width as we
+ * don't need to know.
+ */
+
+test_cputype:
+ /* See if shifts wrap - if so it's an 8086 or 8088 */
+ movw $0x121,%cx
+ shl %cl,%ch
+ jne is808x
+
+ /* So it's a 186 or better. See if the push sp quirk is fixed */
+ pushw %sp
+ popw %bx
+ cmpw %bx,%sp
+ /* 286 or better fix the push sp funny */
+ jne is8028x
+ /* 186 ? */
+ movb $3,%al
+ ret
+is808x:
+ /* See if we have an NEC V20/V30 */
+ xorb %al,%al /* Z */
+ movb $40,%al
+ mul %al
+ jne notnec
+ movb $2,%al
+ ret
+notnec:
+ /* See if we have the prefix rep fail bug. On a non CMOS 8086
+ the CPU restarts the instruction only allowing for the last
+ prefix - so the rep is forgotten only the es is used. interrupts
+ must be enabled and the timer running for this check */
+ /* Needs to be enough loops that we guarantee an IRQ hits but not
+ too many more */
+ movw $0xffff,%cx
+ rep lodsb %es:(%si) /* Spin for IRQ */
+ jcxz cmos86
+ xorw %ax,%ax
+ ret
+cmos86:
+ movb 1,%al
+ ret
+is8028x:
+ /* 286 or higher, We can trivially check for 386 but we just
+ don't care about it */
+ movb $4,%al
+ ret
+
+/*
+ * Call this only for older processors. It won't give a valid
+ * answer for a 286. It can only be run once and self modifies.
+ */
+bus_width_test:
+ pushw %di
+ xorw %dx,%dx
+ pushf
+ pushw %ds
+ cli
+ movw %cs,%ax
+ movw %ax,%ds
+ lea patch+2,%di
+ movb $0x90,%al
+ movw $3,%cx
+ std
+ rep stosb
+ nop
+ nop
+ nop
+ nop
+patch: inc %dx
+ nop
+ nop
+ popw %ds
+ popf
+ popw %di
+ testw %dx,%dx
+ je eightbit
+ movb $16,bus_width
+ ret
+eightbit:
+ movb $8,bus_width
+ ret
+test_fputype:
+ fninit
+ movw $0x55AA, scratch
+ fnstsw scratch
+ cmpb $0,scratch
+ jne no_fpu
+ fnstcw scratch
+ movw scratch,%ax
+ andw $0x103F,%ax
+ cmpw $0x3F,%ax
+ jne no_fpu
+ andw $0xff7f,%ax /* clear interrupt bit - FIXME do we need ? */
+ fldcw scratch
+ fdisi
+ fstcw scratch
+ testb $80,scratch /* Did the int bit change */
+ jnz fpu_8087
+ /* 287 or better - do we care about 387 probably not */
+ movb $2, fpu_type
+ ret
+fpu_8087:
+ movb $1, fpu_type
+ ret
+no_fpu:
+ movb $0, fpu_type
+
+/*
+ * Must be called with interrupts on and a timer running. When this
+ * completes we know the processor type, the fpu type (if any) and
+ * the bus width 8 v 16bit
+ *
+ * We don't detect anything beyond 286 because we don't care about
+ * any features beyond that. Detecting processor clock rate is rather
+ * tricky (the PC/AT for example runs at 1 wait state) and we don't
+ * really have a use for that either - so we don't.
+ */
+cpu_detect:
+ call test_fputype
+ call test_cputype
+ movb %al,cpu_type
+ cmpb $4,%al
+ je always_16bit
+ jmp bus_width_test
+always_16bit:
+ movb $16,bus_width
+ ret
/* FIXME: extract from C library or write nice ones */
__ashlsi3:
/* FIXME */
abort:
jmp trap_monitor
+
+ .data
+
+scratch:
+ .word 0
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