This device was added by Dave Poirier (eks@void-core.2y.net).
Compiling Bochs with iodebug support
./configure --enable-iodebug makeOther optional fields may be added to the ./configure line, see Bochs documentation for all the information. To enable the iodebug plugin at runtime, it must be loaded with the 'plugin_ctrl' bochsrc option.
Using the I/O Interface to the debugger port range: 0x8A00 - 0x8A01 Port 0x8A00 servers as command register. You can use it to enable the i/o interface, change which data register is active, etc. Port 0x8A01 is used as data register for the memory monitoring.
0x8A00 Used to enable the device. Any I/O to the debug module before this command is sent is sent will simply be ignored. 0x8A01 Selects register 0: Memory monitoring range start address (inclusive) 0x8A02 Selects register 1: Memory monitoring range end address (exclusive) 0x8A80 Enable address range memory monitoring as indicated by register 0 and 1 and clears both registers 0x8AE0 - Return to Debugger Prompt If the debugger is enabled (via --enable-debugger), sending 0x8AE0 to port 0x8A00 after the device has been enabled will return the Bochs to the debugger prompt. Basically the same as doing CTRL+C. 0x8AE2 - Instruction Trace Disable If the debugger is enabled (via --enable-debugger), sending 0x8AE2 to port 0x8A00 after the device has been enabled will disable instruction tracing 0x8AE3 - Instruction Trace Enable If the debugger is enabled (via --enable-debugger), sending 0x8AE3 to port 0x8A00 after the device has been enabled will enable instruction tracing 0x8AE4 - Register Trace Disable If the debugger is enabled (via --enable-debugger), sending 0x8AE4 to port 0x8A00 after the device has been enabled will disable register tracing. 0x8AE5 - Register Trace Enable If the debugger is enabled (via --enable-debugger), sending 0x8AE5 to port 0x8A00 after the device has been enabled will enable register tracing. This currently output the value of all the registers for each instruction traced. Note: instruction tracing must be enabled to view the register tracing 0x8AFF Disable the I/O interface to the debugger and the memory monitoring functions.
Note: all accesses must be done using word
Note: reading this register will return 0x8A00 if currently activated, otherwise 0
All accesses to this port must be done using words. Writing to this port will shift to the left by 16 the current value of the register and add the provided value to it.
Sample: reg0 = 0x01234567 out port: 0x8A01 data: 0xABCD reg0 = 0x4567ABCD
Enable memory monitoring on first page of text screen (0xb8000-0xb8fa0): add in bochrc file: optromimage1: file="asmio.rom", address=0xd0000
/*
* Make asmio ROM file:
* gcc -c asmio.S
* objcopy -O binary asmio.o asmio.rom
*/
.text
.global start
.code16
/* ROM Header */
.byte 0x55
.byte 0xAA
.byte 1 /* 512 bytes long */
start:
/* Monitor memory access on first page of text screen */
mov $0x8A00,%dx /* Enable iodebug (0x8A00->0x8A00) */
mov %dx,%ax
out %ax,%dx
mov $0x8A01,%ax /* Select register 0 start addr (0x8A01->0x8A00) */
out %ax,%dx
mov $0x8A01,%dx /* Write start addr 0xB8000 (high word first) */
mov $0xB,%ax
out %ax,%dx
mov $0x8000,%ax /* Write start addr (low word) */
out %ax,%dx
mov $0x8A02,%ax /* Select register 1 end addr (0x8A02->0x8A00) */
mov $0x8A00,%dx
out %ax,%dx
mov $0x8A01,%dx /* Write end addr 0xB8FA0 (high word first) */
mov $0xB,%ax
out %ax,%dx
mov $0x8FA0,%ax /* Write end addr (low word) */
out %ax,%dx
mov $0x8A00,%dx /* Enable addr range memory monitoring (0x8A80->0x8A00) */
mov $0x8A80,%ax
out %ax,%dx
mov $0x8A00,%dx /* Return to Bochs Debugger Prompt (0x8AE0->0x8A00) */
mov $0x8AE0,%ax
out %ax,%dx
lret
.byte 0x6b /* Checksum (code dependent!, update it as needed) */
.align 512 /* NOP follow */