On Nov 29, 2007, at 11:55 AM, Nils Nieuwejaar wrote: > On Thu 11/29/07 at 11:34 AM, Tim.Marsland at Sun.COM wrote: >>> To ensure that this new PV-aware cmdk is only loaded in HVM >>> domains, we >>> propose to install it in a new directory: /platform/i86hvm/kernel/ >>> drv. In >>> HVM domains, this new directory will be prepended to the default >>> module >>> search path. Just to be clear: we are not proposing to create a >>> whole new >>> 'implementation' called i86hvm. This is just for the PV drivers. >> >> How will that prepending happen, exactly? > > I'm still working on the 'exactly'. It will probably involve a > change in > either startup_modules() or kobj_init(), but I just started looking > into > this. > > The 'generally' is that Xen provides a cpuid instruction that > allows us to > determine whether this is an HVM domain and, if so, which version > of Xen we > are running on. On non-Xen platforms, this cpuid instruction > returns an > error. > > If we determine we are running in an hvm domain on a supported > version of > Xen, we will add /platform/i86hvm/kernel to the beginning of the > default > search path. Otherwise, we will leave the search path untouched, and > Solaris will access all devices through the (possibly emulated) > physical > interfaces.
But up until now (my understanding was) we didn't have to touch the kernel to make these PV drivers work. There's considerable advantage in the perception that we're just adding drivers, rather than patching the kernel .. (Were you *already* patching the kernel and I just didn't realize it?) tim
