[Qemu-devel] Re: [PATCH] RTL8139: Latch C+ mode state instead of inferring it from C+ Command register

[Anthony Liguori <anthony@codemonkey.ws>]

Avi Kivity wrote:
> It was observed that Windows 2003 x64 hangs when shutting down if an
> RTL8139 NIC and a USB device tablet are both present.  What seems to be
> happening is:
>
> - the guest shuts down the transmitter and receiver
> - time passes
> - the guest requests a tally counter dump
>
> As it happens, the tally counter command register overlaps the transmit
> status register in C mode.  Qemu determines whether the chip is in C or C+
> mode by looking at the C+ transmit enable bit; as this is now unset, the
> dump tally counter command is interpreted as a C mode transmit command.  The
> guest doesn't think so, however, and continues to poll for completion of the
> tally counter dump command.  This never occurs, so the guest hangs.
>
> Fix by redefining C+ mode as "a write to the C+ command register has occurred
> since the last reset".  The data sheet is silent on the matter.
>
> Signed-off-by: Avi Kivity <avi@redhat.com>
>
>   
Applied.  Thanks.

Regards,

Anthony Liguori