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annotate level2/modules/kernel/ccbkrn.txt @ 3195:6eb2edad80d8

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L2: Introduce symbol KrnBlk to define kernel block number This is the block number that the kernel is loaded into. This is platform-specific, a function of the behaviour of the platform MMU/DAT. CRCs are unaffected by this change.
author Neal Crook <foofoobedoo@gmail.com>
date Thu, 01 Jun 2017 22:13:49 +0100
parents 530759e9f289
children
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 * I eliminated the manual padding of the kernel. I inserted a fill
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2 directive much further down in the source between the "regular"
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3 module part of the kernel, and the fe00 page code. Down at that end
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4 the assembler will auto-compute the size needed
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5
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6 * At entry, the kernel now pulls the size of the bootfile from the U
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7 stack, which is still setup from CCB, and saves it to
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8 its proper place in the DP. Also misc. DP flags are set - if boot
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9 was attempted, and CPU speed is set (CCB uses high speed for coco3)
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10
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11 * at entry, the kernel now installs it's own debug printing and crash
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12 routines, something that REL used to do.
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13
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14 * there's a place where some IRQ-ish tables are copied down to the DP,
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15 where I found a bug: reg Y was being filled with a bogus source
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16 address. I'm NOT good with PCR addressing, but after fixing, my code
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17 changes started working....maybe you want to verify this change.
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18
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19 * read comments in the "calculate memory size" section... I got way
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20 lucky on this one!
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21
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22 * the biggest functional changes occur at label L0170:
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23
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24 - The kernel no longer verifies itself (and hense adds itself to the
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25 modules directory), it now verifies itself and the preloaded
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26 bootfile together. The kernel no longer reserves it's own memory
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27 either, it now simply calls f$srqmem to do this for us and the
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28 bootfile together as one big block.
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29
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30 - AFTER reserving system memory and verifying, we now mark up the
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31 sysDAT... I don't understand why we have to do this. Shouldn't
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32 f$rsysmem do this for us?!?!
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33
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34 - we link to init and set CRC checking and jump to krnp2's exec.
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35
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36 * Near commented out label L01D2, I've commented out this section, it
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37 no longer needed as f$rsysmem DOES do this for the entire kernel
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38 now, not just the bootfile
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39
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40 * the code at L01DF can be "inlined", nothing calls it but one place.
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41 One of the IRQ vectors borrow's this routine's RTS though ... goofy
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42 speghetti code!
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43
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44 * AFTER all the normal included system call files, and BEFORE the FE00
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45 page stuff near label S.SysIRQ I added automatic padding
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46
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47 * S.SysIRQ which is supposed to be in FE page, assembles at around
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48 fdf1 or so.... which according to the comments is a BAD thing.
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49 Nothing seems to happen. Basically, the FE page code it TOO BIG to
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50 fit!
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51
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52
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53 And in f$srqmem.asm:
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54
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55 * I modified this system call to request memory starting from 0xff00
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56 rather than ed00... it might be a touch lesss efficient AFTER
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57 booting, but it sure helped DURING booting. This is how I reused
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58 fsrqmem to setup the KRN and OS9BOOT file in one swoop.
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59
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60 * I changed f$boot to just issue a kernel panic. I'm not sure if this
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61 is the thing to do. KRNP2 calls f$boot on chdir and open default
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62 device error. I'm not sure if anything else calls it. Maybe it can
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63 be it can be deleted and KRNP2 changed just to panic itself rather
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64 than system calling to do so.
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65
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66
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67 *** All changes were made to a fresh CVS'd copy of Nitros9 Version 3.2.9.
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68 *** I have no idea if this all works on a coco2 or a 6309
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69
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70
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71 *** CoCoBoot / OS9 Contract:
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72
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73 - Size of the pre-loaded bootfile (NOT boot and cckrn) is passed as
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74 the top 2 bytes on the U stack. MSB on top... the usually motorola
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75 byte order. In Forth lingo, the top cell of the data stack is the
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76 size of the bootfile. Calling the kernel works and appears just like
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77 calling any other forth word, except we don't return, e.i.:
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78
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79 : gotokernel ( u -- ) \ jump to kernel passing it u - the bootfile
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80 \ size in bytes, this funtion doesn't return.
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81
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82 - Module CCBKRN is loaded to block 0x3f at offset 0x1000, or 0xf000 in
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83 cpu-space. CCBKRN must be exactly 0x0f00 in size and be in a
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84 standard os9 executable module format.
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85
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86 - The OS9Boot file is loaded on a page boundary just low enough in
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87 cpu-space to fit below 0xf000 (the CCBKRN module) physical blocks
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88 are allocated in order starting with block 0x01 (or 0x31 on a 128k
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89 machine).
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90
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91 - The source of OS9Boot and CCBKRN is not guaranteed!
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92
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93 - Register Guarantees:
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94 D - not guaranteed
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95 DP - not guaranteed
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96 X - not guaranteed
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97 Y - not guaranteed but usually will be in the 0x3800-0x6000 range
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98 U - set to top of a stack usually in the 0x7e00-0x7f00
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99 S - not guaranteed but usually will be in the 0x7f00 - 0x8000 range
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100 CC - not guaranteed.
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101
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102 - MMU Guarantees:
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103 physical block 0x3f will be banked in at 0xe000-0xff00 in cpu-space
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104
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105
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106
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107
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108 *** CoCoBoot does this but maybe CCBKRN should do instead:
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109
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110 - physical block 0x00 is in cpu-space at 0x0000 upon calling to
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111 CCBKRN. DP is set to 0x00 and the DP area in block 0x00 is cleared.
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112
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113 - CPU interrupts and Pia0 side B's interrupts are disabled.
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114
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115 - memory map is guaranteed to look like this (in hex):
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116
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117 00 39 3a 3b 3c 3d 3e 3f
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118
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119 - Physical Block 3b will be cleared to spaces except offset 0x0000:
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120 will be initialized to 0x0008. This serves as a screen pointer to
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121 kernel debug printing.
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122
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123 - The GIME registers will be set as follows:
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124
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Boisy Pitre <boisy.pitre@nuance.com>
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diff changeset
125 starting at 0xff90:
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
126 6c init0
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
127 00 init1
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
128 00 irq enable
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
129 00 firq enable
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
130 0900 timer register
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
131 0000 unused
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
132 0320 screen settings
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
133 0000 ????
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
134 00 ????
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
135 ec01 physical video address (block 3b offset 0x0008 )
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
136 00 horizontal offset / scroll
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
137
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
138 A mirror of these bytes will appear at 0x0090-0x009f in the DP
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
139
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
140
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
141
530759e9f289 Added ccbkrn from Brett Gordon (level 2 only for now)
Boisy Pitre <boisy.pitre@nuance.com>
parents:
diff changeset
142 Brett M. Gordon