Re: [PATCH v2 1/3] hw/net: e1000: Correct the initial value of VET register

[Bin Meng]

On Mon, Jul 5, 2021 at 12:21 PM Jason Wang <jasowang@redhat.com> wrote:
>
>
> 在 2021/7/2 下午5:24, Bin Meng 写道:
> > From: Christina Wang <christina.wang@windriver.com>
> >
> > The initial value of VLAN Ether Type (VET) register is 0x8100, as per
> > the manual and real hardware.
> >
> > While Linux e1000 driver always writes VET register to 0x8100, it is
> > not always the case for everyone. Drivers relying on the reset value
> > of VET won't be able to transmit and receive VLAN frames in QEMU.
> >
> > Reported-by: Markus Carlstedt <markus.carlstedt@windriver.com>
> > Signed-off-by: Christina Wang <christina.wang@windriver.com>
> > Signed-off-by: Bin Meng <bin.meng@windriver.com>
> > ---
> >
> > (no changes since v1)
> >
> >   hw/net/e1000.c | 2 ++
> >   1 file changed, 2 insertions(+)
> >
> > diff --git a/hw/net/e1000.c b/hw/net/e1000.c
> > index 4f75b44cfc..20cbba6411 100644
> > --- a/hw/net/e1000.c
> > +++ b/hw/net/e1000.c
> > @@ -29,6 +29,7 @@
> >   #include "hw/pci/pci.h"
> >   #include "hw/qdev-properties.h"
> >   #include "migration/vmstate.h"
> > +#include "net/eth.h"
> >   #include "net/net.h"
> >   #include "net/checksum.h"
> >   #include "sysemu/sysemu.h"
> > @@ -254,6 +255,7 @@ static const uint32_t mac_reg_init[] = {
> >       [MANC]    = E1000_MANC_EN_MNG2HOST | E1000_MANC_RCV_TCO_EN |
> >                   E1000_MANC_ARP_EN | E1000_MANC_0298_EN |
> >                   E1000_MANC_RMCP_EN,
> > +    [VET]     = ETH_P_VLAN,
>
>
> I wonder if we need a compat flag for this, since we change the behavior.
>
> (See e1000_properties[])
>

No we don't need to since it does not break migration.

Regards,
Bin