Re: [Xen-devel] RTL8139 support

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

> > Capturing this would be very helpful, particularly if debuging in
> > the RTL8139 driver was enabled. Comparing it against the same
> > driver running under Linux would likely highlight the problem.
> 
> Following your advice, I've made some progress now.  I noticed that
> booting Fedora, dmesg listed a sensible MAC and IRQ, and had identified
> my chip set as "RTL-8139C" (lspci -n reports 10ec:8139 for the device). 
> However Xen reported "unknown chip version, assuming RTL-8139" and
> "TxConfig = 0x0".  It appears all the RTL_R[8,16,32] macros in 8139too.c
> were returning zero, so I've defined USE_IO_OPS so they call in[b,w,l]
> like 3c59x.c instead of read[b,w,l].  The patch is attached, as well as
> the resulting log output.  The good news is that this identifies the
> chip set properly and reports the correct MAC.  I can even configure the
> device with ifconfig and send packets onto the network.
> 
> Naturally there's some bad news too - receiving packets hangs the
> machine instantly.  Although pinging an unused address is OK, the return
> packet from a live address stalls Xen.  Similar problems were
> experienced with a DHCP offer response and even trying to send UDP
> packets with nc.
> 
> Does anybody have any experience of this working since being added to
> Xen, or have any thoughts on how I might proceed debugging it?

Accesses to the skb->data on the receive path must be wrapped with
map_domain_mem()/unmap_domain_mem(). 

eg. 
 char *vdata = map_domain_mem(__pa(skb->data));
 <use vdata as you would normally use skb->data>
 unmap_domain_mem(vdata);

I've taken a brief look at the driver and you may get away with just
replacing wth_copy_and_sum() in include/xeno/etherdevice.h with the
following:

static inline void eth_copy_and_sum(struct sk_buff *dest, 
       unsigned char *src, int len, int base)
{
    char *vdata = map_domain_mem(__pa(dest->data));
    memcpy(vdata, src, len);
    unmap_domain_mem(vdata);
}

(You may need to #include <asm/domain_page.h>).

 -- Keir


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