[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Confused about Xen memory management.
On Wednesday 16 February 2005 14:08, Nakajima, Jun wrote: > There are notions like "guest/pseudo physical" and "machine physical" in > Xen. Guest physical is basically virtualized physical address space, and > that's the one the bulk of the guest kernel code looks at. That way many > assumptions in the kernel are met, thus we can minimize changes to the > kernel when para-virtualizing. Machine physical is real one (i.e. global > and unique), and the guest needs to use machine physical especially for > inter-domain communications or MMU-related hypercalls typically. BTW, there's a virt_to_machine() macro available for convenience. Cheers, Mark > The macro pfn_to_mfn() converts guest physical PFN to machine PFN. > So what you need to do is to give the machine address to Xen like: > > (pfn_to_mfn(__pa(foo) >> PAGE_SHIFT) << PAGE_SHIFT) + (foo & (PAGE_SIZE > - 1)) > > Jun > -----Original Message----- > From: xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx > [mailto:xen-devel-admin@xxxxxxxxxxxxxxxxxxxxx] On Behalf Of Rusty > Russell > Sent: Tuesday, February 15, 2005 10:22 PM > To: Xen Mailing List > Subject: [Xen-devel] Confused about Xen memory management. > > OK, so I am implementing a prototype where Linux hands an address into > Xen, which gets decremented later (ie. when Xen is executing a different > domain). It seems that map_domain_mem() is what I want, but how do I > get the physical address of the variable? virt_to_phys() in Linux > doesn't seem to do the trick, nor virt_to_phys() in Xen. > > ie, pseudo code: > > linux/mydriver.c: > static int foo = 1; > > // virt_to_phys(foo) maybe? > HYPERVISOR_mytest(&foo); > > xen/common/test.c: > int mytest(unsigned long addr) > { > // virt_to_phys(addr) maybe? > manip_later->addr = addr; > return 0; > } > > // Some time later > ... > int *p = map_domain_mem(manip_later->addr); > (*p)++; > unmap_domain_mem(p); > > Sorry for the stupid question; I hate VM. > Rusty. ------------------------------------------------------- SF email is sponsored by - The IT Product Guide Read honest & candid reviews on hundreds of IT Products from real users. Discover which products truly live up to the hype. Start reading now. http://ads.osdn.com/?ad_id=6595&alloc_id=14396&op=click _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/xen-devel
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