---
title: the Linux Kernel KConfig model sample
...

The model comes from the [ASE paper](http://gsd.uwaterloo.ca/node/251)

```clafer
abstract tristate
    module ?

MISC_FILESYSTEMS ?
    display -> string = "Miscellaneous filesystems"
    
    JFFS2_FS : tristate ?
        display -> string = "Journalling Flash File System"
        [MTD]
        [MTD => CRC32]

        FFS2_FS_DEBUG -> int
            [this = 0] // default
            display -> string = "JFFS2 Debug level (0=quiet, 2=noisy)"
            [0 <= this && this <= 2]

        JFFS2_FS_WRITEBUFFER ?
        [JFFS2_FS_WRITEBUFFER <=> HAS_IOMEM] // default

        JFFS2_COMPRESS ?
            display -> string = "Advanced compression options for JFFS2"
            
            [JFFS2_ZLIB] // default
            JFFS2_ZLIB ?
                display -> string = "Compress w/zlib..."
                [ZLIB_INFLATE]

            CompressionChoice
                display -> string = "Default compression"
                [JFFS2_CMODE_PRIORITY] // default
                xor choice
                    JFFS2_CMODE_NONE
                        display -> string = "no compression"
                    JFFS2_CMODE_PRIORITY
                        display -> string = "priority"
                    JFFS2_CMODE_SIZE
                        display -> string = "size (EXPERIMENTAL)"
```

Below are dummy clafer names used in the model above.

```clafer
MTD
CRC32
HAS_IOMEM
ZLIB_INFLATE
```