Messages in this thread | | | Subject | Re: [RFC PATCH kernel] Revert "net/mlx4_core: Set UAR page size to 4KB regardless of system page size" | From | Alexey Kardashevskiy <> | Date | Wed, 16 Mar 2016 13:07:58 +1100 |
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On 03/15/2016 09:40 PM, Or Gerlitz wrote: > On Tue, Mar 15, 2016 at 12:19 PM, Alexey Kardashevskiy <aik@ozlabs.ru> wrote: >> This reverts commit 85743f1eb34548ba4b056d2f184a3d107a3b8917. >> >> Without this revert, POWER "pseries" KVM guests with a VF passed to a guest >> using VFIO fail to bring the driver up: >> >> mlx4_core: Mellanox ConnectX core driver v2.2-1 (Feb, 2014) >> mlx4_core: Initializing 0000:00:00.0 >> mlx4_core 0000:00:00.0: enabling device (0000 -> 0002) >> mlx4_core 0000:00:00.0: Detected virtual function - running in slave mode >> mlx4_core 0000:00:00.0: Sending reset >> mlx4_core 0000:00:00.0: Sending vhcr0 >> mlx4_core 0000:00:00.0: HCA minimum page size:512 >> mlx4_core 0000:00:00.0: UAR size:4096 != kernel PAGE_SIZE of 65536 >> mlx4_core 0000:00:00.0: Failed to obtain slave caps > >> Both host and guest use 64K system pages. >> >> How to fix this properly? Thanks. > > The commit message says: > > "[..] Regarding backward compatibility in SR-IOV, if hypervisor has > this new code, the virtual OS must be updated. [...]"
So with v4.5 as a host, there is no actual distro available today to use as a guest in the next 6 months (or whatever it takes to backport this partucular patch back there).
You could have added a module parameter to enforce the old behavoir, at least...
And sorry but from the original commit log I could not understand why exactly all existing guests need to be broken. Could you please point me to a piece of documentation describing all this UAR bisuness (what is UAR, why 128 UARs are required and for what, etc). Thanks.
-- Alexey
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