I am using a analog / digital I/O card in many projects (DMM-16-AT from Diamond Systems), which is a PC/104 (ISA equivalent) card.The problem is, that there are 8 digital outputs at address BASE + 3 which are 0V at boot, but 5V (logic 1) after about 10 sec in boot process. I'm suspecting that another kernel driver or program or etc is writing at this address. Is there any way to monitor writes to a specitic address to track down the issue?Note : the base address is 0x300, also the total bootup of Linux is about 45 seconds so it is not related to my own program.From the datasheet :Base + 3 Write Digital Output Port        +-------+-------+-------+-------+-------+-------+-------+-------+Bit No. |     7 |     6 |     5 |     4 |     3 |     2 |     1 |     0 |        +-------+-------+-------+-------+-------+-------+-------+-------+Name    | DOUT7 | DOUT6 | DOUT5 | DOUT4 | DOUT3 | DOUT2 | DOUT1 | DOUT0 |        +-------+-------+-------+-------+-------+-------+-------+-------+These pins correspond directly to the same named pins on I/O connector J3.On power up or reset, the output register is cleared to all zeroes.
Monitor I/O writes to ISA card
linux kernel;io
You can tell the kernel not to probe some addresses.  From man bootparam: reserve=iobase,extent[,iobase,extent]...The reserve boot-time argument specifies an I/O port region that      shouldn't be probed.  A device driver will not probe a  reserved      region,  unless  another boot argument explicitly specifies that      it do so. reserve=0x300,32  blah=0x300keeps all device drivers except the driver for 'blah' from probing 0x300-0x31f.Of course, it still might be the bootloader (eg grub) that is doing the probe.