Question on DCMD values for custom messages..

QNX USERS QNX6 - OS
1

Hi ,

I have a question on the dcmd value I can use with __DIOTF(_DCMD_MISC, dcmd, data) for my custom messages. I saw the below warning while reading some QNX document on the range of values reserved for QSSL.

/*(Note that the range of dcmd values you can use is limited (0x0000 through 0xfff inclusive is reserved for QSSL). */

What is the safe range of dcmd values I can use to process my custom commands while calling io_devctl() ?

==============================================================================================================
#define MY_CMD_CODE 100 // Is this safe value to use for _DCMD_MISC class ?

#define FPGA_READ __DIOTF(_DCMD_MISC, MY_CMD_CODE + 1, FpgaAccessIPC_ST)
#define FPGA_READ_BLOCK __DIOTF(_DCMD_MISC, MY_CMD_CODE + 2, FpgaAccessIPC_ST)
#define FPGA_READ_BLOCK_SERIES __DIOTF(_DCMD_MISC, MY_CMD_CODE + 3, FpgaAccessIPC_ST)

Let me know if you have any questions on this? Hope I am clear in my question.

Thanks for your time.

2

It`s not, it should be 0x1000 ( 0xfff + 1 ).

3

Thanks Mario. Is there any upper limit for the same ?

4

Yes. Take a look at /usr/include/devctl. The system uses upper bits in the dcmd to indicate which way the data is flowing.