[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: [ PATCH 2.6.16-rc3-xen 3/3] sysfs: export Xen hypervisor attributes to sysfs
On Wed, 2006-02-22 at 22:26 -0600, Anthony Liguori wrote: > Arjan van de Ven wrote: > > On Wed, 2006-02-22 at 08:43 -0500, Mike D. Day wrote: > > > >> Heiko Carstens wrote: > >> > >>> On Wed, Feb 22, 2006 at 08:06:12AM -0500, Mike D. Day wrote: > >>> > >>> If it's not needed, why include it at all? > >>> > >> Sorry for not being clear. It *is* needed for control tools and agents > >> running in the privileged domain. > >> > > > > but again those tools and agents *already* have a way of talking to the > > hypervisor themselves. Why can't they just first ask this info? Why does > > that need to be in the kernel, in unswappable memory? > > > Hypercalls have to be done in ring 0 for security reasons) There has to > be some kernel interface for making hypercalls. sure but you need that ANYWAY; the management tools will want a generic "THIS hypercall" thing > > The current interface is a ioctl() on a /proc file (which is awful). > The ioctl just pretty much passes 5 word arguments to the hypervisor. > It was suggested previously here that a hypercall pass-through interface > isn't the right approach. One suggestion that came up was a syscall > interface. yeah a syscall sounds right for this > Also, there are some kernel-level drivers, like the memory ballooning > driver, that only exist in the kernel. Controlling the balloon driver > requires some sort of interface. That was the original point of this > effort (since it's currently exposed as a /proc file). I think it's > quite clear that the balloon driver should expose itself through sysfs > but I'm not personally convinced that this information (hypervisor > version information) ought to be exposed in sysfs. that's a different thing; the ballooning driver obviously has to be in kernel due to how it interacts with the VM, and having it's 1 or 2 controls in sysfs (hint: make it writable module parameters, so that the defaults can be set at module load time, and you'll also get the rest for free ;) pure hypervisor info... no. "only" 8Kb of code + all data structures.. for something just as easily done in the management layer. In fact I suspect the management layer will do the hypercalls anyway just because it's easier to do than parsing sysfs ! _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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