Re: Number of the max supported VFs are different

On 3/3/22 03:55, Yalan Zhang wrote: > Hi there, > > I have an Intel X520 network card, and I find the max supported VFs are > different. > Please check below outputs: > > # lspci -vvv -s 04:00.0 > 04:00.0 Ethernet controller: Intel Corporation Ethernet 10G 2P X520 > Adapter (rev 01) > ... > Capabilities: [160 v1] Single Root I/O Virtualization (SR-IOV) > IOVCap: Migration-, Interrupt Message Number: 000 > IOVCtl: Enable- Migration- Interrupt- MSE- ARIHierarchy+ > IOVSta: Migration- > ** Initial VFs: 64, Total VFs: 64**, Number of VFs: 0, Function > Dependency Link: 00 > VF offset: 128, stride: 2, Device ID: 10ed > Supported Page Size: 00000553, System Page Size: 00000001 > Region 0: Memory at 0000000094400000 (64-bit, prefetchable) > Region 3: Memory at 0000000094500000 (64-bit, prefetchable) > VF Migration: offset: 00000000, BIR: 0 > Kernel driver in use: ixgbe > Kernel modules: ixgbe > > # cat /sys/class/net/enp4s0f0/device/sriov_totalvfs > 63 > > # echo 64 > /sys/class/net/enp4s0f0/device/sriov_numvfs > -bash: echo: write error: Numerical result out of range > # echo 63 > /sys/class/net/enp4s0f0/device/sriov_numvfs > # cat /sys/class/net/enp4s0f0/device/sriov_numvfs > 63 > > The lspci command says the Total VFs supported is 64, while in the file > "sriov_totalvfs" says it's 63. > And the sriov_numvfs file will take precedence. > Why are the numbers different? Just a little curious. I believe this comes from the driver implementation: /* ixgbe driver limit the max number of VFs could be enabled to * 63 (IXGBE_MAX_VF_FUNCTIONS - 1) */ #define IXGBE_MAX_VFS_DRV_LIMIT (IXGBE_MAX_VF_FUNCTIONS - 1) https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/d... Michal