The sis 900 only works if promiscuous mode is set.

Notes:
Thu Feb 16 09:20:58 EST 2006 rsc
    I am skeptical about this.  Do other drivers for the
    sis900 take this step?  Surely there's just something
    we're not initializing right.
    


Reference: /n/sources/patch/sorry/sis900-hack
Date: Wed Feb 15 13:34:02 CET 2006
Reviewed-by: rsc

--- /sys/src/9/pc/ether83815.c	Wed Feb 15 13:32:17 2006
+++ /sys/src/9/pc/ether83815.c	Wed Feb 15 13:32:10 2006
@@ -81,7 +81,7 @@
 
 enum {				/* Variants */
 	Nat83815	= (0x0020<<16)|0x100B,
-	Sis900 = (0x0630<<16)|0x1039,	/* untested */
+	Sis900 = (0x0900<<16)|0x1039,	/* untested */
 };
 
 typedef struct Ctlr Ctlr;
@@ -301,6 +301,7 @@
 	Ctlr *ctlr;
 	ulong w;
 
+	debug("promiscuous: %s\n", on ? "on" : "of");
 	ctlr = ((Ether*)arg)->ctlr;
 	ilock(&ctlr->lock);
 	w = csr32r(ctlr, Rrfcr);
@@ -971,6 +972,12 @@
 	ctlr->ntdr = Ntde;
 	pcisetbme(ctlr->pcidev);
 	ctlrinit(ether);
+
+	/*
+	  * The sis 900 only works in promiscuous mode.
+	  */
+	if(ctlr->id == Sis900)
+		promiscuous(ether, 1);
 
 	/*
 	 * Linkage to the generic ethernet driver.