| Name | Size | Last modified (GMT) | Description | |
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| Parent directory | 2024-11-11 14:29:33 | ||
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| Makefile | 126 bytes | 2024-11-11 14:29:33 | |
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| README | 5470 bytes | 2024-11-11 14:29:33 | |
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| config.c | 6841 bytes | 2024-11-11 14:29:33 | |
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| q40.h | 168 bytes | 2024-11-11 14:29:33 | |
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| q40ints.c | 8121 bytes | 2024-11-11 14:29:33 |
1 Linux for the Q40 2 ================= 3 4 You may try http://www.geocities.com/SiliconValley/Bay/2602/ for 5 some up to date information. Booter and other tools will be also 6 available from this place or http://ftp.uni-erlangen.de/pub/unix/Linux/680x0/q40/ 7 and mirrors. 8 9 Hints to documentation usually refer to the linux source tree in 10 /usr/src/linux/Documentation unless URL given. 11 12 It seems IRQ unmasking can't be safely done on a Q40. IRQ probing 13 is not implemented - do not try it! (See below) 14 15 For a list of kernel command-line options read the documentation for the 16 particular device drivers. 17 18 The floppy imposes a very high interrupt load on the CPU, approx 30K/s. 19 When something blocks interrupts (HD) it will lose some of them, so far 20 this is not known to have caused any data loss. On highly loaded systems 21 it can make the floppy very slow or practically stop. Other Q40 OS' simply 22 poll the floppy for this reason - something that can't be done in Linux. 23 Only possible cure is getting a 82072 controller with fifo instead of 24 the 8272A. 25 26 drivers used by the Q40, apart from the very obvious (console etc.): 27 drivers/char/q40_keyb.c # use PC keymaps for national keyboards 28 serial.c # normal PC driver - any speed 29 lp.c # printer driver 30 genrtc.c # RTC 31 char/joystick/* # most of this should work, not 32 # in default config.in 33 block/floppy.c # normal PC driver, DMA emu in asm/floppy.h 34 # and arch/m68k/kernel/entry.S 35 # see drivers/block/README.fd 36 ata/pata_falcon.c 37 net/ne.c 38 video/q40fb.c 39 parport/* 40 sound/dmasound_core.c 41 dmasound_q40.c 42 43 Various other PC drivers can be enabled simply by adding them to 44 arch/m68k/config.in, especially 8 bit devices should be without any 45 problems. For cards using 16bit io/mem more care is required, like 46 checking byte order issues, hacking memcpy_*_io etc. 47 48 49 Debugging 50 ========= 51 52 Upon startup the kernel will usually output "ABCQGHIJ" into the SRAM, 53 preceded by the booter signature. This is a trace just in case something 54 went wrong during earliest setup stages of head.S. 55 **Changed** to preserve SRAM contents by default, this is only done when 56 requested - SRAM must start with '%LX$' signature to do this. '-d' option 57 to 'lxx' loader enables this. 58 59 SRAM can also be used as additional console device, use debug=mem. 60 This will save kernel startup msgs into SRAM, the screen will display 61 only the penguin - and shell prompt if it gets that far.. 62 Unfortunately only 2000 bytes are available. 63 64 Serial console works and can also be used for debugging, see loader_txt 65 66 Most problems seem to be caused by fawlty or badly configured io-cards or 67 hard drives anyway. 68 Make sure to configure the parallel port as SPP and remove IRQ/DMA jumpers 69 for first testing. The Q40 does not support DMA and may have trouble with 70 parallel ports version of interrupts. 71 72 73 Q40 Hardware Description 74 ======================== 75 76 This is just an overview, see asm-m68k/* for details ask if you have any 77 questions. 78 79 The Q40 consists of a 68040@40 MHz, 1MB video RAM, up to 32MB RAM, AT-style 80 keyboard interface, 1 Programmable LED, 2x8bit DACs and up to 1MB ROM, 1MB 81 shadow ROM. 82 The Q60 has any of 68060 or 68LC060 and up to 128 MB RAM. 83 84 Most interfacing like floppy, IDE, serial and parallel ports is done via ISA 85 slots. The ISA io and mem range is mapped (sparse&byteswapped!) into separate 86 regions of the memory. 87 The main interrupt register IIRQ_REG will indicate whether an IRQ was internal 88 or from some ISA devices, EIRQ_REG can distinguish up to 8 ISA IRQs. 89 90 The Q40 custom chip is programmable to provide 2 periodic timers: 91 - 50 or 200 Hz - level 2, !!THIS CAN'T BE DISABLED!! 92 - 10 or 20 KHz - level 4, used for dma-sound 93 94 Linux uses the 200 Hz interrupt for timer and beep by default. 95 96 97 Interrupts 98 ========== 99 100 q40 master chip handles only a subset of level triggered interrupts. 101 102 Linux has some requirements wrt interrupt architecture, these are 103 to my knowledge: 104 (a) interrupt handler must not be reentered even when sti() is called 105 from within handler 106 (b) working enable/disable_irq 107 108 Luckily these requirements are only important for drivers shared 109 with other architectures - ide,serial,parallel, ethernet. 110 q40ints.c now contains a trivial hack for (a), (b) is more difficult 111 because only irq's 4-15 can be disabled - and only all of them at once. 112 Thus disable_irq() can effectively block the machine if the driver goes 113 asleep. 114 One thing to keep in mind when hacking around the interrupt code is 115 that there is no way to find out which IRQ caused a request, [EI]IRQ_REG 116 displays current state of the various IRQ lines. 117 118 Keyboard 119 ======== 120 121 q40 receives AT make/break codes from the keyboard, these are translated to 122 the PC scancodes x86 Linux uses. So by theory every national keyboard should 123 work just by loading the appropriate x86 keytable - see any national-HOWTO. 124 125 Unfortunately the AT->PC translation isn't quite trivial and even worse, my 126 documentation of it is absolutely minimal - thus some exotic keys may not 127 behave exactly as expected. 128 129 There is still hope that it can be fixed completely though. If you encounter 130 problems, email me ideally this: 131 - exact keypress/release sequence 132 - 'showkey -s' run on q40, non-X session 133 - 'showkey -s' run on a PC, non-X session 134 - AT codes as displayed by the q40 debugging ROM 135 btw if the showkey output from PC and Q40 doesn't differ then you have some 136 classic configuration problem - don't send me anything in this case 137
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