+/*
+ * variables set up by front end.
+ */
+extern int mfs; /* run as the memory based filesystem */
+extern int Nflag; /* run mkfs without writing file system */
+extern int Oflag; /* format as an 4.3BSD file system */
+extern int fssize; /* file system size */
+extern int ntracks; /* # tracks/cylinder */
+extern int nsectors; /* # sectors/track */
+extern int nphyssectors; /* # sectors/track including spares */
+extern int secpercyl; /* sectors per cylinder */
+extern int sectorsize; /* bytes/sector */
+extern int rpm; /* revolutions/minute of drive */
+extern int interleave; /* hardware sector interleave */
+extern int trackskew; /* sector 0 skew, per track */
+extern int headswitch; /* head switch time, usec */
+extern int trackseek; /* track-to-track seek, usec */
+extern int fsize; /* fragment size */
+extern int bsize; /* block size */
+extern int cpg; /* cylinders/cylinder group */
+extern int cpgflg; /* cylinders/cylinder group flag was given */
+extern int minfree; /* free space threshold */
+extern int opt; /* optimization preference (space or time) */
+extern int density; /* number of bytes per inode */
+extern int maxcontig; /* max contiguous blocks to allocate */
+extern int rotdelay; /* rotational delay between blocks */
+extern int maxbpg; /* maximum blocks per file in a cyl group */
+extern int nrpos; /* # of distinguished rotational positions */
+extern int bbsize; /* boot block size */
+extern int sbsize; /* superblock size */
+extern u_long memleft; /* virtual memory available */
+extern caddr_t membase; /* start address of memory based filesystem */
+extern caddr_t malloc(), calloc();
+