[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: XEN/IA64 VHPT support
> Probably you can rely on us for the long format VHPT although > the detail plan is not done yet. BTW, for the hypercall, I am thinking > how it will be implemented in IA64 architecture. I think a straight > forward way is to use break instruction like linux system call, any idea > in your mind? Re LVHPT. Please let me know if you work on it as it has been something I've been wanting to get done for some time, mostly because it will make simulations run faster too. So if you don't get to it soon, I might work on it, and it would be bad if we both finished at the same time :-) Re hypercalls. Actually there are hypercalls already in Xen/ia64 and they do use the break instruction. It's just that the domain calls them indirectly so perhaps they are better called "hyperthunks" ("Thunk" is a rarely used compiler term which originated in Algol 60 that means: "code that is used to convert calls to one interface into calls to another"): When a domain is created, fake EFI/SAL/PAL (firmware) calls are created that contain the hypercalls. Thus when domain0 invokes an EFI/SAL/PAL call, it calls a "stub" routine that invokes a break instruction/fault that is recognized in Xen/ia64 as a hypercall, with arguments passed in general registers (unlike Xen/x86 which passes hypercall arguments in memory). You may want to step through a domain0 firmware call to see this work. If I recall correctly, the code that creates the hyperthunks is in arch/ia64/dom_fw.c While my intent is to use the same mechanism (breaks) for "real" hypercalls, I also want to explore the use of fast system calls (recently added in Linux/ia64 by David Mosberger) using the epc instruction in certain cases. Dan ------------------------------------------------------- The SF.Net email is sponsored by: Beat the post-holiday blues Get a FREE limited edition SourceForge.net t-shirt from ThinkGeek. It's fun and FREE -- well, almost....http://www.thinkgeek.com/sfshirt _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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