paper over very bad queue behavior when recv(queue, 0) and recv(queue, 1)
contend over the same queue by disabling the transmit proc for ethernet
devices that would like to do their own receive.

Reference: /n/atom/patch/applied2013/fsamd64ether
Date: Tue Aug 27 23:23:45 CES 2013
Signed-off-by: quanstro@quanstro.net

--- /sys/src/fs/amd64/ether82563.c	Tue Aug 27 23:22:45 2013
+++ /sys/src/fs/amd64/ether82563.c	Tue Aug 27 23:22:45 2013
@@ -926,7 +926,6 @@
 		td->control = Ide|Rs|Ifcs|Teop|BLEN(bp);
 		ctlr->tb[tdt] = bp;
 		tdt = Next(tdt, m);
-extern void sfence(void);
 		sfence();
 		csr32w(ctlr, Tdt, tdt);
 	}
@@ -1729,7 +1728,8 @@
 	 */
 	edev->attach = i82563attach;
 	edev->interrupt = i82563interrupt;
-	edev->transmit = i82563transmit;
+//	edev->transmit = i82563transmit;
+	edev->transmit = nil;
 
 //	edev->arg = edev;
 
--- /sys/src/fs/amd64/fns.h	Tue Aug 27 23:22:45 2013
+++ /sys/src/fs/amd64/fns.h	Tue Aug 27 23:22:45 2013
@@ -1,19 +1,10 @@
 #include "../port/portfns.h"
 
-/* junk */
-void	waveprint(char*, ...);
-void	wave(int);
-#pragma	varargck argpos	waveprint	1
-
-void	vunmap(void*, usize);
-#define	machcolor(m)	-1
 void	acpiinit(int);
-
 int	adec(int*);
 int	ainc(int*);
 void	apmmuinit(void);
 int	archmmu(void);
-#define BIOSSEG(a)	KADDR(((uint)(a))<<4)
 void	cgaputc(int);
 void	cgaputs(char*, int);
 void	cmd_e820(int, char**);
@@ -48,6 +39,7 @@
 int	kbdgetc(void);
 void	kbdinit(void);
 int	kbdintr0(void);
+#define	machcolor(m)	-1
 void	mfence(void);
 void	microdelay(int);
 void	mmuinit(void);
@@ -72,6 +64,7 @@
 void	puttr(u64int);
 u64int	rdmsr(int);
 vlong	rdtsc(void);
+void	sfence(void);
 void	sipi(void);
 Mpl	splhi(void);
 Mpl	spllo(void);
@@ -89,12 +82,16 @@
 int	vmapsync(uintptr);
 void*	vmap(uintmem, usize);
 void	vsvminit(int);
+void	vunmap(void*, usize);
+void	wave(int);
+void	waveprint(char*, ...);
 void	wrmsr(int, vlong);
+#define BIOSSEG(a)	KADDR(((uint)(a))<<4)
+
+#pragma	varargck argpos	waveprint	1
 
 #define PTR2UINT(p)	((uintptr)(p))
 #define UINT2PTR(i)	((void*)(i))
-
-//#define PCIWADDR(a)	PADDR(a)
 
 /* pata */
 void	ideinit(Device*);
--- /sys/src/fs/amd64/etherif.c	Tue Aug 27 23:22:45 2013
+++ /sys/src/fs/amd64/etherif.c	Tue Aug 27 23:22:45 2013
@@ -81,70 +81,6 @@
 	}
 }
 
-#ifdef no
-static void
-ethero(void)
-{
-	Ether *ether;
-	Ifc *ifc;
-	Msgbuf *mb;
-	int len;
-
-	ether = u->arg;
-	ifc = &ether->ifc;
-	print("ether%do: %E %I\n", ether->ctlrno, ifc->ea, ifc->ipa);	
-
-	for(;;) {
-		mb = recv(ifc->reply, 1);
-		if(mb == nil)
-			continue;
-
-		len = mb->count;
-		if(len > ether->ifc.maxmtu){
-			print("ether%do: pkt too big - %d\n", ether->ctlrno, len);
-			mbfree(mb);
-			continue;
-		}
-		if(len < ETHERMINTU) {
-			memset(mb->data+len, 0, ETHERMINTU-len);
-			mb->count = len = ETHERMINTU;
-		}
-		memmove(((Enpkt*)(mb->data))->s, ifc->ea, sizeof(ifc->ea));
-
-		ilock(&ether->tqlock);
-		if(ether->tqhead)
-			ether->tqtail->next = mb;
-		else
-			ether->tqhead = mb;
-		ether->tqtail = mb;
-		mb->next = 0;
-		iunlock(&ether->tqlock);
-
-		ether->transmit(ether);
-
-		ifc->work.count++;
-		ifc->rate.count += len;
-		ifc->txpkt++;
-	}
-}
-
-Msgbuf*
-etheroq(Ether* ether)
-{
-	Msgbuf *mb;
-
-	mb = nil;
-	ilock(&ether->tqlock);
-	if(ether->tqhead){
-		mb = ether->tqhead;
-		ether->tqhead = mb->next;
-	}
-	iunlock(&ether->tqlock);
-
-	return mb;
-}
-#endif
-
 /*
  * look, ma.  no extra queue.
  */
@@ -155,6 +91,13 @@
 
 	e = u->arg;
 	print("ether%do: %E %I\n", e->ctlrno, e->ifc.ea,  e->ifc.ipa);
+
+	/* should not be necessary; scheduling sucks */
+	if(e->transmit == nil){
+		static Rendez r[MaxEther];
+		for(;;)
+			tsleep(r + e->ctlrno, no, 0, 10000);
+	}
 
 	for(;;){
 		recv(e->ifc.reply, 0);	// wait for something to do.