Building an OS image

An OS image is created by a program called mkifs (make image filesystem), which accepts information from two main sources: its command line and a buildfile. You can change the buildfile to configure the OS image.

The diagram below shows the how mkifs uses rules from the buildfile to combine OS and user executables, shared objects and data files to create an OS image, which can be transfered to the target system and booted.

Figure 1. How mkifs creates an OS image.

For more information about mkifs, see mkifs in the Utilities Reference; for more information about the OS image buildfile, see the OS Image Buildfiles chapter.

You may also want to use the diskimage utility, which creates an image for a partitioned medium. The partitioned medium image can contain any number of filesystem images (for example, Power-Safe filesystems that were created using mkqnx6fsimg or mkqnx6fs).

Generating the OS image

Once you have configured the buildfile, you need to generate the image file. To generate the image file using a buildfile called shell.bld, on your host system you could execute the command:

mkifs shell.bld shell.ifs

This command tells mkifs to use the buildfile shell.bld to create the image file shell.ifs.

You can also specify command-line options to mkifs. Since these command-line options are interpreted before the actual buildfile, you can add lines before the buildfile. You can do this if you want to use a makefile to change the defaults of a generic buildfile.

The following example changes the address at which the image starts to 64 KB (hex 0x10000):

mkifs -l "[image=0x10000]" buildfile image

For more information, see mkifs in the Utilities Reference.

Listing the contents of an image

If want to see the contents of an image after you have built it, you can use the dumpifs utility. The output from dumpifs might look something like this:

   Offset     Size  Name
        0      100  Startup-header flags1=0x1 flags2=0 paddr_bias=0x80000000
      100     a008  startup.*
     a108       5c  Image-header mountpoint=/
     a164      264  Image-directory
     ----     ----  Root-dirent
     ----       12  usr/lib/ -> /proc/boot/
     ----        9  dev/console -> /dev/ser1
     a3c8       80  proc/boot/.script
     b000    4a000  proc/boot/procnto
    55000    59000  proc/boot/ 
     ----        9  proc/boot/ -> 
    ae000     7340  proc/boot/devc-ser8250
    b6000     4050  proc/boot/esh
    bb000     4a80  proc/boot/ls
    c0000    14fe0  proc/boot/data1
    d5000     22a0  proc/boot/data2
Checksums: image=0x94b0d37b startup=0xa3aeaf2

The more -v (“verbose”) options you specify to dumpifs, the more data you'll see.

For more information about dumpifs, see its entry in the Utilities Reference.