Don't error during initialization.
 [jmk] --rw-rw-r-- M 551037 glenda sys 23556 Dec  1 14:19 sys/src/9/pc/ether83815.c
	/n/sourcesdump/2005/1201/plan9/sys/src/9/pc/ether83815.c:594,606 - 
	/n/sourcesdump/2005/1202/plan9/sys/src/9/pc/ether83815.c:594,609
	  	ctlr = ether->ctlr;
	  
	  	/*
	- 	 * Allocate and initialise the receive ring;
	- 	 * allocate and initialise the transmit ring;
	- 	 * unmask interrupts and start the transmit side
	+ 	 * Allocate suitable aligned descriptors
	+ 	 * for the transmit and receive rings;
	+ 	 * initialise the receive ring;
	+ 	 * initialise the transmit ring;
	+ 	 * unmask interrupts and start the transmit side.
	  	 */
	- 	ctlr->rdr = malloc(ctlr->nrdr*sizeof(Des));
	- 	if (ctlr->rdr == nil)
	- 		error(Enomem);
	+ 	des = xspanalloc((ctlr->nrdr+ctlr->ntdr)*sizeof(Des), 32, 0);
	+ 	ctlr->tdr = des;
	+ 	ctlr->rdr = des+ctlr->ntdr;
	+ 
	  	last = nil;
	  	for(des = ctlr->rdr; des < &ctlr->rdr[ctlr->nrdr]; des++){
	  		des->bp = iallocb(Rbsz);
	/n/sourcesdump/2005/1201/plan9/sys/src/9/pc/ether83815.c:616,622 - 
	/n/sourcesdump/2005/1202/plan9/sys/src/9/pc/ether83815.c:619,624
	  	ctlr->rdrx = 0;
	  	csr32w(ctlr, Rrxdp, PADDR(ctlr->rdr));
	  
	- 	ctlr->tdr = xspanalloc(ctlr->ntdr*sizeof(Des), 8*sizeof(ulong), 0);
	  	last = nil;
	  	for(des = ctlr->tdr; des < &ctlr->tdr[ctlr->ntdr]; des++){
	  		des->cmdsts = 0;