[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-ia64-devel] [PATCH][RFC][TAKE4] the P2M/VP patches
On Fri, Apr 07, 2006 at 03:57:30PM +0800, Tian, Kevin wrote: > >> Does this patch only save one hypercall overhead? We can always > >> tell guest the auto_translated bit is true when guest hypercalls to > >> query feature bits into xen_feature array. > > > >No. > >I agree that we can go without this patch by telling the bit always 1. > >The reasons why I wrote this patch are as follows > > > >- It is more explicit than telling auto_translated bit always 1. > > Perhaps code readers expect that the auto_translated feature > > can be determined at run-time even for xen/ia64, not requirement. > > This is only a readability issue. > > Telling auto_translated bit 1 makes code harder-to-read a bit. > > > >- Compiler can optimize better. > > Maybe I'm not clear here. You can see from setup_xen_features > where a hypercall is issued to query what on earth this domain is > configured with. That feature info can be passed in from config file. > So I think even xen/ia64 wants to hardcode auto_translated bit as 1, > it's better to do within xen with xenlinux inferface unchanged to query. > Anyway, we don't want to eliminate future possibility that dom0 may > also see physmap directly for performance. :-) But yes, seems this > feature need to be queried earlier which seems difficult for current > xen/ia64 model. So it may be better to hardcode xen_features array > for now. > > How do you think? In fact I wondered that this patch was acceptable. I guess that xen/x86 people will be against this patch saying similar things. This patch is not important, just for my preference. I drop this patch. -- yamahata _______________________________________________ Xen-ia64-devel mailing list Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-ia64-devel
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