Does mmap in NetBSD-current work as expected?  I get the following
error message from this piece of code from XFree86 when calling mmap.

checkDevMem: warning: failed to mmap /dev/mem (Invalid argument)
	linear fb access unavailable

if ((fd = open("/dev/mem", O_RDWR)) < 0)
	{
	    if (warn)
	    {
	        ErrorF("checkDevMem: warning: failed to open /dev/mem (%s)\n",
		       strerror(errno));
	        ErrorF("\tlinear fb access unavailable\n");
	    }
	    useDevMem = FALSE;
	    return;
	}
	/* Try to map a page at the VGA address */
	base = (pointer)mmap((caddr_t)0, 4096, PROT_READ|PROT_WRITE,
			     MAP_FILE, fd, (off_t)0xA0000);
	close(fd);
	if (base == (pointer)-1)
	{
	    if (warn)
	    {
	        ErrorF("checkDevMem: warning: failed to mmap /dev/mem (%s)\n",
		       strerror(errno));
	        ErrorF("\tlinear fb access unavailable\n");
	    }
	    useDevMem = FALSE;
	    return;
	}
	munmap((caddr_t)base, 4096);
	useDevMem = TRUE;
	return;


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