fdisk issue

[Erik Wikström]

On 2007-08-11 13:37, Michael Neumann wrote:
Hi,

I had experienced that my laptop's BIOS hangs up when I don't specify
fdisk's -C option! The source code in question in fdisk.c follows:
    if (tcyl > MAXCYL && C_flag == 0) {
      printf("Warning: starting cylinder wraps, using all 1's\n");
      partp->dp_scyl = -1;
      partp->dp_ssect = -1;
      partp->dp_shd = -1;
    } else {
      partp->dp_scyl = DOSCYL(tcyl);
      partp->dp_ssect = DOSSECT(tsec,tcyl);
      partp->dp_shd = thd;
    }
I'd like to understand why we set dp_* to -1. Is there a special reason? 
FreeBSD just ignores this and executes the "else" part.