On Fri, Aug 09, 2024 at 11:31:15PM +0100, Conor Dooley wrote: > On Tue, Aug 06, 2024 at 05:31:36PM -0700, Charlie Jenkins wrote: > > xtheadvector is a custom extension that is based upon riscv vector > > version 0.7.1 [1]. All of the vector routines have been modified to > > support this alternative vector version based upon whether xtheadvector > > was determined to be supported at boot. > > > > vlenb is not supported on the existing xtheadvector hardware, so a > > devicetree property thead,vlenb is added to provide the vlenb to Linux. > > > > There is a new hwprobe key RISCV_HWPROBE_KEY_VENDOR_EXT_THEAD_0 that is > > used to request which thead vendor extensions are supported on the > > current platform. This allows future vendors to allocate hwprobe keys > > for their vendor. > > > > Support for xtheadvector is also added to the vector kselftests. > > So uh, since noone seems to have brought it up, in the light of the issues > with thead's vector implementation, (https://ghostwriteattack.com/) do we > want to enable it at all? I can make it clear in the kconfig that xtheadvector is succeptible to this attack and that it should be enabled with caution. I think we should let people that understand the risk to enable it. - Charlie
