From: Yanming Liu <yanminglr@xxxxxxxxx> Sent: Wednesday, January 19, 2022 12:14 PM > > On Thu, Jan 20, 2022 at 2:12 AM Michael Kelley (LINUX) > <mikelley@xxxxxxxxxxxxx> wrote: > > > > From: Wei Liu <wei.liu@xxxxxxxxxx> Sent: Friday, January 14, 2022 11:13 AM > > > > > > On Mon, Jan 10, 2022 at 01:44:19AM +0100, Andrea Parri wrote: > > > > (Extending Cc: list,) > > > > > > > > On Sun, Jan 09, 2022 at 05:55:16PM +0800, Yanming Liu wrote: > > > > The VSS driver in hv_snapshot.c allocates a receive buffer of 8 Kbytes > > and sets max_pkt_size to 8 Kbytes. But the received messages are > > all fixed size and small. I don't know why the driver uses an 8 Kbyte > > receive buffer instead of 4 Kbytes, but the current settings are > > more than sufficient. > > > > Well, I'm not sure, on August 2021 there was a patch changing > max_pkt_size to 8 KiB for VSS driver: > https://lore.kernel.org/linux-hyperv/20210825190217.qh2c6yq5qr3ntum5@liuwe-devbox-debian-v2/T/ > > The patch mentioned a 6304 bytes VSS message. Which is part of the > reason I tried to address the more "general" problem of potentially > mismatching buffer size. > This is certainly interesting. The Linux driver is not processing all those bytes, so I'm not sure what Hyper-V is passing to the guest. I'll check with the Hyper-V team to be sure. Michael
