[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] Re: How is the virt_hv_start_low used in compatible guest
The guest can (and is actually doing so in the Dom0 case) make use of this e.g. for setting the low/highmem boundary at a higher address, thus increasing the amount of lowmem over what that would be on a 32-bit hypervisor. For DomU-s to also benefit, the tools would need to be adjusted, but as this can affect where a guest can be migrated to, so far it didn't seem worthwhile for anybody to actually implement this. Jan >>> "Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx> 06.07.09 11:20 >>> Jan/Keir, I have a question to followin code In arch/x86/domain_build.c. Can you share me why we need to make the virt_start be adjustable based on the memory size in the system? Per my understanding, these changes will only affect HV itself, but I didn't see much benifit. Or did I missed anything? Thanks Yunhong Jiang if ( (parms.virt_hv_start_low != UNSET_ADDR) && elf_32bit(&elf) ) { unsigned long mask = (1UL << L2_PAGETABLE_SHIFT) - 1; value = (parms.virt_hv_start_low + mask) & ~mask; BUG_ON(!is_pv_32bit_domain(d)); #if defined(__i386__) if ( value > HYPERVISOR_VIRT_START ) panic("Domain 0 expects too high a hypervisor start address.\n"); #else if ( value > __HYPERVISOR_COMPAT_VIRT_START ) panic("Domain 0 expects too high a hypervisor start address.\n"); HYPERVISOR_COMPAT_VIRT_START(d) = max_t(unsigned int, m2p_compat_vstart, value); #endif } _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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