Controlling FreeMiNT's real FAT XFS

last update: 1998-10-06 Author: Frank Naumann fnaumann@freemint.de notes:

I. Introduction

FreeMiNT 1.15 has a new FAT filesystem. It is integrated in the kernel.

The NEWFATFS has many advantages:

• very fast
• mostly configurable also on runtime
• supports Microsofts VFAT extension
• supports TOS and DOS partitions of any size
• supports FAT32 partitions; partitions larger than 2 GB are no longer a problem
• part of FreeMiNT, available in source for easy support

At the moment the old TOS filesystem is the default filesystem. This will change in the future.

To activate the new FAT filesystem (NEWFATFS), there is a new configuration keyword to use in the configuration file (MiNT.CNF). With a line like "NEWFATFS=A,D,E,F" the NEWFATFS will be active on A:, D:, E: and F: (valid FAT partition only)

VFAT can be configured at boot time in the configuration file with "VFAT=" keyword (same syntax as NEWFATFS).

Write back cache can be activated at boottime with "WB_ENABLE=" keyword (same syntax as NEWFATFS).

VFAT and write back cache configuration is only available for NEWFATFS partitions (and MinixFS 0.70 partitions).

The following paragraphs describe the supported calls for runtime configuration. Only interesting for programmers. It exists the tool FSetter from Christian Felsch that implemented all these configuration in an easy GEM program. FSetter is part of FreeMiNT 1.15 distribution. Thanks to Christian Felsch for this.

II. Definition

Prototype:

long Dcntl (short opcode, const char *path, long arg);

call conventions:

• all arguments are on the stack
• return value is stored in d0 (cdecl call)

return value conventions:

• negative return values are ATARI error codes
• if opcode doesn't exist or is not supported EINVFN is returned

type conventions:

char 8 bit signed unsigned char 8 bit unsigned short 16 bit signed integer unsigned short 16 bit unsigned integer long 32 bit signed integer unsigned long 32 bit unsigned integer llong 64 bit signed integer ullong 64 bit unsigned integer

with:

typedef struct { long hi; unsigned long low; } llong;
typedef struct { unsigned long hi; unsigned long low; } ullong;

 III. Supported opcodes