|
|       execute NetBSD kernel
|
|       written by ITOH Yasufumi
|       public domain
|
|       $NetBSD: execkern.S,v 1.4 2011/02/21 02:31:58 itohy Exp $

#include <machine/asm.h>
#include "execkern.h"

#define MFP             0x00E88000      /* MFP */
#define MFP_IERA        (MFP+0x07)      /* (B) interrupt enable reg A */
#define MFP_IERB        (MFP+0x09)      /* (B) interrupt enable reg B */
#define MFP_RSR         (MFP+0x2B)      /* (B) USART receiver status reg */

#ifndef SRAM_MEMSZ
#define SRAM            0x00ED0000      /* SRAM start addr */
#define SRAM_MEMSZ      (SRAM + 8)      /* (L) size of main memory */
#endif

|       a3+0    load address
|
|       a3+4    section #1 image top address
|       a3+8    section #1 size
|       a3+12   section #1 gap size
|         :       :
|       a3+n-12 section #XK_NSEC image top address
|       a3+n-8  section #XK_NSEC size
|       a3+n-4  section #XK_NSEC gap size
|
|       a3+n    (reserved) (d5)
|       a3+n+4  bootdev (d6)
|       a3+n+8  boothowto (d7)
|       a3+n+12 entry address (absolute address)

#ifndef XK_NO_C_INTERFACE
        .text
        .even
ENTRY_NOPROFILE(exec_kernel)
        addql   #4,%sp
        moveal  %sp@+,%a3               | struct execkern_arg *
#endif

        moveal  %a3@+,%a1               | load address
        movel   %a1,%d3

        |
        | copy image
        |

        movel   #XK_NSEC-1,%d2
Lloop:
        moveal  %a3@+,%a0               | section image address
        movel   %a3@+,%d0               | section size
        movel   %d0,%d1
        jbsr    copy
        movel   %a3@+,%d0               | section gap
        jbsr    clear

        dbra    %d2,Lloop

        | stop MFP interrupts (for compatibility)
        clrb    MFP_IERA
        clrb    MFP_IERB
        clrb    MFP_RSR

        |
        | execute kernel
        | start(load_addr, mem_max, kernel_end)
        |
        movel   %a1,%d0
        addql   #3,%d0
        andib   #0xFC,%d0
        subl    %d3,%d0
        movel   %d0,%sp@-               | arg #3 (end of kernel)
        movel   SRAM_MEMSZ,%sp@-        | arg #2 (RAM size from SRAM)
        movel   %d3,%sp@-               | arg #1 (load address)

#if 0
        movel   %a3@+,%d5               | (reserved)
        movel   %a3@+,%d6               | boot device
        movel   %a3@+,%d7               | boot howto

        movel   %a3@+,%a0               | entry address
#else   /* optimized */
        moveml  %a3@+,%d5-%d7/%a0
#endif

        | clear unused registers
        moveq   #0,%d0
        moveq   #0,%d1
        moveq   #0,%d2
        moveq   #0,%d3
        moveq   #0,%d4
        moveal  %d0,%a1
        moveal  %d0,%a2
        moveal  %d0,%a3
        moveal  %d0,%a4
        moveal  %d0,%a5
        moveal  %d0,%a6

        jsr     %a0@                    | execute NetBSD kernel
        | NOTREACHED

        | ??? returned from kernel -- issue software reset
        subal   %a1,%a1
        moveml  0x00ff0000,#0x0101      | get RESET vectors (%d0: ssp, %a0: pc)
        moveml  #0x0101,%a1@            | put them at 0x00000000 (for Xellent)
        .long   0x4E7B9801              | movec %a1,%vbr
        jmp     %a0@                    | go to reset address


|
| utility routines
|

| copy %d0 bytes from higher (%a0) to lower (%a1) address
1:      moveb   %a0@+,%a1@+
copy:   subql   #1,%d0
        bpls    1b
        rts

| clear %d0 bytes at %a1
| do nothing if %d0 is zero
1:      clrb    %a1@+
clear:  subql   #1,%d0
        bpls    1b
        rts