On 9/22/08, David Miller <davem@xxxxxxxxxxxxx> wrote: > From: Anthony Liguori <anthony@xxxxxxxxxxxxx> > Date: Mon, 22 Sep 2008 14:34:21 -0500 > > > > Blue Swirl wrote: > > > But I think we could already start early drafting of what KVM support > > > for Sparc32 and Sparc64 would mean. Because of certain problems in the > > > V9 instruction set design (V8 rett reuse for example), it may be > > > difficult or even impossible to use an accelerator if the host and > > > target instruction sets do not match. > > > > I don't know much about the Sparc architecture, but the embedded > > PowerPC port that Hollis has spear-headed is for an architecture > > that does not natively support hardware virtualization. As long as > > Sparc meets all of the requirements to do this sort of > > virtualization (all privileged instructions are trappable when run > > in non-privileged mode), it should be rather straight forward. > > > As he mentioned, the V8 rett instruction causes problems on V9 chips. > > An opcode which was a V8 privileged instruction, "rett", got reused as > a non-privileged instruction in V9, for "return". There are others: rdtbr/flushw and stdfq/stqf. Also any ASI >0x80 accesses are unprivileged on V9, though that shouldn't be a problem since all ASIs used on V8 were <0x80. And of course MMUs are incompatible. > So booting a 32-bit kernel on a 64-bit cpu is going to be challenging, > at best. Maybe it would be possible to run V8 userspace with full speed acceleration on V9 and use translation only for kernel code? -- To unsubscribe from this list: send the line "unsubscribe sparclinux" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
