source: soft/giet_vm/giet_boot/boot_entry.S @ 492

Last change on this file since 492 was 490, checked in by haoliu, 10 years ago

Implemented a new way to construct the ptabs in boot. In the map.bin file,
each physical segment in cluster[x][y] is handled by the processor[x][y][0]. So
the constrcuting of page table is done in parrallel by all the
processor[x][y][0] at the same time.

This way spents less time than the constructing sequential by one processor(
the processor[0][0][0])
File size: 3.4 KB
Line 
1/*
2 * file   : boot.S
3 * date   : 01/17/2014
4 * author : Cesar Fuguet & Alain Greiner & Hao Liu
5 *
6 * This file contains the boot_entry() function that is the entry
7 * point for the GIET_VM bootloader.
8 * It supports a generic multi-clusters / multi-processors architecture,
9 * containing at most 1024 processors.
10 * - The number of clusters is defined by the (X_SIZE,Y_SIZE) parameters
11 *   in the hard_config.h file (up to 256 clusters).
12 * - The number of processors per cluster is defined by the NB_PROCS_MAX
13 *   parameter in the hard_config.h file (up to 4 processors per cluster).
14 *
15 * This assembly code is executed by all processors.
16 * It initializes the stack pointer depending on the proc_id,
17 * and using the SEG_BOOT_STACK_BASE and SEG_BOOT_STACK_SIZE
18 * parameters defined in the hard_config.h file, and jumps
19 * to the boot_init() fuction defined in the boot.c file.
20 *
21 * - each processor[x][y][0] uses a larger stack: 1,25 Kbytes.
22 * - Other processors use a smaller stack:    256 bytes.
23 *     => the SEG_BOOT_STACK_SIZE cannot be smaller 512 Kytes.
24 *         (256*(1024+256) + (1024 - 256) * 256 = 512 Kbytes = 0x80000)
25 */
26
27    #include "mips32_registers.h"
28    #include "hard_config.h"
29
30    .section .text,"ax",@progbits
31
32    .globl  boot_entry
33    .ent    boot_entry
34
35    .align  2
36    .set noreorder
37
38boot_entry:
39
40
41    /* All processors compute proc_id = (cluster_id * NBPROCS) + lpid             */
42    /* where cluster_id = (x * Y_SIZE) + y                                        */
43    /* The (x,y,lpid) values are obtained from the processor CP0 register,        */
44    /* where  proc_xyl == (((x<<4) + y) * NB_PROCS_MAX) + lpid                    */
45    /* (proc_id is a "continuous" index, while proc_xyl is a "fixed format" index */
46
47
48    mfc0   k0,      CP0_PROCID
49    andi   k0,      k0,     0xFFF             /* k0 <= proc_xyl                   */
50    andi   t1,      k0,     ((1<<P_WIDTH)-1)  /* t1 <= lpid                       */
51    srl    t2,      k0,     P_WIDTH           /* t2 <= cluster_xy                 */
52    srl    t3,      t2,     Y_WIDTH           /* t3 <= x coordinate               */
53    andi   t4,      t2,     ((1<<Y_WIDTH)-1)  /* t4 <= y coordinate               */
54    la     t6,      Y_SIZE                    /* t6 <= Y_SIZE                     */
55    multu  t3,      t6
56    mflo   t5
57    addu   t5,      t5,     t4                /* t5 <= cluster_id                 */
58    li     t6,      0x100 * (NB_PROCS_MAX - 1) + 0x500  /* stack size per cluster */
59    multu  t6,      t5
60    mflo   t7
61
62    /* All processors initializes stack pointer, depending on proc_id             */
63
64   la      k0,      SEG_BOOT_STACK_BASE
65   addu    k0,      k0,     t7
66   li      k1,      0x500           /* k1 <= local P0 stack size == 1,25 Kbytes            */
67   addu    sp,      k0,     k1      /* P0 stack from base to (base + stack size * cluster_id + 1,25K )         */
68
69   li      k1,      0x100           /* k1 <= Pi stack size == 256 bytes            */
70   multu   k1,      t1             
71   mflo    k0                       /* k0 <= 256 * proc_id                        */
72   addu    sp,      sp,     k0      /* Pi stacks from base + stack size * cluster_id + 1,25K + proc_id*256    */
73
74
75    /* All processors jump to the boot_init function                              */
76
77    la     k0,     boot_init
78    jr     k0
79    nop
80
81    .end boot_entry
82
83    .set reorder
84
85/*
86 * vim: tabstop=4 : shiftwidth=4 : expandtab
87 */
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