Plan 9 dhcpd.c modifications for PXE booting Raspberry Pi 3 and Pi 4

dhcpd_diffs.out

diff ./dhcpd.c /n/sources/plan9/sys/src/cmd/ip/dhcpd/dhcpd.c
1143d1142
< 	char ipaddrstr[NDB_IPlen];
1263,1267d1261
< 		case ODtftpserver:	/* RPi4s request it for no-SD netbooting without hardcoding TFTP_IP in EEPROM */
< 			memset(ipaddrstr, 0, sizeof(ipaddrstr));
< 			sprint(ipaddrstr, "%I", rp->up->laddr);
< 			stringopt(rp, ODtftpserver, ipaddrstr);
< 			break;
1289,1308d1282
< 
< 		/* point back to packet, encapsulate vopts into packet */
< 		j = rp->p - vopts;
< 		rp->p = op;
< 		rp->max = omax;
< 		vectoropt(rp, OBvendorinfo, vopts, j);
< 	}else if(strncmp((char*)rp->vendorclass, "PXEClient", 9) == 0){
< 		/* raspberry pi 3 */
< 		/* https://www.raspberrypi.org/documentation/hardware/raspberrypi/bootmodes/net.md */
< 		/* raspberry pi 4 */
< 		/* https://www.raspberrypi.org/documentation/hardware/raspberrypi/bcm2711_bootloader_config.md */
< 
< 		/* point to temporary area */
< 		op = rp->p;
< 		omax = rp->max;
< 		/* stash encoded options in vopts */
< 		rp->p = vopts;
< 		rp->max = vopts + sizeof(vopts) - 1;
< 
< 		stringopt(rp, OBvendorinfo, "Raspberry Pi Boot   ");