The following patch (relative to NetbSD-current) fixes a bug whereby
KERNTEXTOFF was not defined.  When KERNTEXTOFF is not defined,
kvm_mkdb (src/usr.sbin/kvm_mkdb/nlist.c) falls back to using KERNBASE
instead.  This just doesn't work.  This patch was essential to getting
a working kvm_mkdb.

The patch also hanges MCLBYTES to be big enough to hold an entire
Ethernet frame. This isn't necessary but can't hurt and seems to
improve Ethernet throughput marginally. (The throughput improvement is
Only marginally because, even after tuning IP checksumming and kernel
bcopy, interrupt response seems to be the real limit
 on throughput.)

*** sys/arch/pmax/include/param.h.DIST	Mon Nov 21 14:40:44 1994
--- sys/arch/pmax/include/param.h	Sat Nov 26 23:56:44 1994
***************
*** 67,72 ****
--- 67,73 ----
  #define	SEGSHIFT	22		/* LOG2(NBSEG) */
  
  #define	KERNBASE	0x80000000	/* start of kernel virtual */
+ #define KERNTEXTOFF	0x80030000	/* start of kernel text for kvm_mkdb */
  #define	BTOPKERNBASE	((u_long)KERNBASE >> PGSHIFT)
  
  #define	DEV_BSIZE	512
***************
*** 95,101 ****
   * of the hardware page size.
   */
  #define	MSIZE		128		/* size of an mbuf */
! #define	MCLBYTES	1024
  #define	MCLSHIFT	10
  #define	MCLOFSET	(MCLBYTES - 1)
  #ifndef NMBCLUSTERS
--- 96,102 ----
   * of the hardware page size.
   */
  #define	MSIZE		128		/* size of an mbuf */
! #define	MCLBYTES	2048		/* enough for whole Ethernet packet */
  #define	MCLSHIFT	10
  #define	MCLOFSET	(MCLBYTES - 1)
  #ifndef NMBCLUSTERS