From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:38406) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1VldMC-0000mK-4j for qemu-devel@nongnu.org; Wed, 27 Nov 2013 06:32:40 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1VldM7-0005tX-9G for qemu-devel@nongnu.org; Wed, 27 Nov 2013 06:32:36 -0500 Date: Wed, 27 Nov 2013 19:32:18 +0800 From: Amos Kong Message-ID: <20131127113218.GA6758@amosk.info> References: <1359974470-17044-47-git-send-email-mjt@msgid.tls.msk.ru> <20131127111430.GA4179@amosk.info> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20131127111430.GA4179@amosk.info> Subject: Re: [Qemu-devel] [PATCH 46/60] e1000: Discard oversized packets based on SBP|LPE List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Michael Tokarev Cc: mst@redhat.com, Michael Contreras , jasowang@redhat.com, qemu-devel@nongnu.org, qemu-stable@nongnu.org, stefanha@redhat.com On Wed, Nov 27, 2013 at 07:14:30PM +0800, Amos Kong wrote: > On Mon, Feb 04, 2013 at 02:40:56PM +0400, Michael Tokarev wrote: > > From: Michael Contreras > > > > Discard packets longer than 16384 when !SBP to match the hardware behavior. > > > > Signed-off-by: Michael Contreras > > Signed-off-by: Stefan Hajnoczi > > (cherry picked from commit 2c0331f4f7d241995452b99afaf0aab00493334a) > > > > Signed-off-by: Michael Tokarev > > --- > > hw/e1000.c | 7 +++++-- > > 1 file changed, 5 insertions(+), 2 deletions(-) > > > > diff --git a/hw/e1000.c b/hw/e1000.c > > index e22ba3d..87c798b 100644 > > --- a/hw/e1000.c > > +++ b/hw/e1000.c > > @@ -61,6 +61,8 @@ static int debugflags = DBGBIT(TXERR) | DBGBIT(GENERAL); > > > > /* this is the size past which hardware will drop packets when setting LPE=0 */ > > #define MAXIMUM_ETHERNET_VLAN_SIZE 1522 > > +/* this is the size past which hardware will drop packets when setting LPE=1 */ > > +#define MAXIMUM_ETHERNET_LPE_SIZE 16384 > > > > /* > > * HW models: > > @@ -799,8 +801,9 @@ e1000_receive(VLANClientState *nc, const uint8_t *buf, size_t size) > > } > > > > /* Discard oversized packets if !LPE and !SBP. */ > > - if (size > MAXIMUM_ETHERNET_VLAN_SIZE > > - && !(s->mac_reg[RCTL] & E1000_RCTL_LPE) > > + if ((size > MAXIMUM_ETHERNET_LPE_SIZE || > > + (size > MAXIMUM_ETHERNET_VLAN_SIZE > > + && !(s->mac_reg[RCTL] & E1000_RCTL_LPE))) > > && !(s->mac_reg[RCTL] & E1000_RCTL_SBP)) { > > return size; > > > This change is correct. I have a related question to ask. > > I enabled E1000_DEBUG in qemu, and try to change nic MTU to >1500 > in Windows 7/ Windows 8 guest. I found RCTL register isn't changed. > > It mean E1000_RCTL_LPE bit is 0, so I ping guest from host with > > 1500 size packet, the request ICMP packets will be dropped. > > It seems a e1000 driver bug of Windows? In e1000 driver of Windows, there is a "Jumbo Packet" option, it's used to enable LPE, after enabled Jumbo packet, I can ping guest with large packet (>1500)