Hi David, On Mon, Mar 22, 2021 at 1:24 PM David Gibson <da...@gibson.dropbear.id.au> wrote: > > On Mon, Mar 22, 2021 at 12:33:06PM +0800, Bin Meng wrote: > > Hi David, > > > > On Mon, Mar 22, 2021 at 12:11 PM David Gibson > > <da...@gibson.dropbear.id.au> wrote: > > > > > > On Tue, Mar 16, 2021 at 04:15:05PM +0800, Bin Meng wrote: > > > > As the comment of tx_padding_and_crc() says: "Never add CRC in QEMU", > > > > min_frame_len should excluce CRC, so it should be 60 instead of 64. > > > > > > Sorry, your reasoning still isn't clear to me. If qemu is not adding > > > the CRC, what is? > > > > No one is padding CRC in QEMU. QEMU network backends pass payload > > without CRC in between. > > Ok, but the CRCs must be added if the packets are bridged onto a real > device, yes? Where does that happen?
I've never used it like that before. What's the command line to test that? > > > > > Will it always append a CRC after this padding is complete? > > > > No. > > If that's true, then won't the packets still be shorter than expected > if we only pad to 60 bytes? In QEMU packets are transmitted without CRC between network backends, and when a NIC receives a packet, the minimum required payload length is 60 bytes without a CRC. Regards, Bin
