On Tue, 2022-10-25 at 14:21 +0800, Lei Yu wrote: > > This case is treated as an error and we do not care about the > following data. > Similarly, if we change the MTU in BMC and let BMC ping the OS, the > OS > kernel does not crash and it gets RX errors, and the ping fails. > > # ifconfig usb0 > usb0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500 > ... > RX packets 85 bytes 15380 (15.0 KiB) > RX errors 51 dropped 0 overruns 0 frame 51 > > With this patch, we get the similar behavior on BMC that the RX > errors > are increasing. > > > Additionally, I'm curious, why in this specific case is the device > > sending more data than > > the buffer can hold ? The MTU change should have resulted in > > buffers being re-allocated no ? > > The issue is found in a rare case during BIOS boot, we assume that > BIOS is sending unexpected data to BMC for unknown reasons. Ok thanks. Acked-by: Benjamin Herrenschmidt <benh@xxxxxxxxxxxxxxxxxxx> > > Or did you change the MTU on the remote and not on the local device > > ? > > > > Yes, the MTU is changed to 2000 in OS and kept 1500 on BMC, then the > issue is reproduced. (see detailed steps in the above email). > > The reason we made the above test is because we are trying to > reproduce the behavior as BIOS, and from the logs it looks like it's > sending a packet larger than MTU. Then we tried to adjust the MTU on > the OS side and reproduced the issue.
