On Mon, 2023-01-23 at 18:56 +0200, Oleksii wrote: > Hi Alistair and community, > > I am working on RISC-V support upstream for Xen based on your and > Bobby > patches. > > Adding the RISC-V support I realized that Xen is ran in S-mode. > Output > of OpenSBI: > ... > Domain0 Next Mode : S-mode > ... > So the first my question is shouldn't it be in H-mode?
There is no H-mode in RISC-V. When the Hypervisor extension exists the standard S-mode automatically becomes HS-mode. The two names can be used interchangeably (although the spec calls it HS-mode). In this way Linux (with or without KVM support) and Xen all boot in the same mode and can choose to use virtulisation if desired. > > If I am right than it looks like we have to do a patch to OpenSBI to > add support of H-mode as it is not supported now: > [1] > https://github.com/riscv-software-src/opensbi/blob/master/lib/sbi/sbi_domain.c#L380 > [2] > https://github.com/riscv-software-src/opensbi/blob/master/include/sbi/riscv_encoding.h#L110 > Please correct me if I am wrong. > > The other option I see is to switch to H-mode in U-boot as I > understand > the classical boot flow is: > OpenSBI -> U-boot -> Xen -> Domain{0,...} > If it is at all possible since U-boot will be in S mode after > OpenSBI. S-mode is where you want to be. That's what Xen should start in. Alistair > > Thanks in advance. > > ~ Oleksii
