Hi guys: I am working on Xen 4.0.0. In my project, I need to know the reference number of a paticular page. But I found the result do not match what I think. I need your help. For example, I allocate a buffer in kernel (dom0) char * buf = kmalloc( 4096, ...); Then I use my designed hypercall to read the count_info like this way: // add is the location of the buffer l1_pgentry_t nl1e = guest_map_l1e(current, add, &tmp); unsigned long pfn = 0, mfn = 0; p2m_type_t p2mt = 0; struct page_info *page = NULL; pfn = l1e_get_pfn(nl1e); mfn = mfn_x( gfn_to_mfn( current->domain, pfn, &p2mt ) ); debug_trace(printk("pfn %lx, mfn %lx, p2mt %x nl1e.l1 %llx\n", pfn, mfn, p2mt, nl1e.l1)); // here I check the validation of mfn, then try to get page page = mfn_to_page(mfn); debug_trace(printk("page count %lx, marked count %lx, page typeinfo %lx\n", page->count_info, page->count_info & PGC_count_mask, page->u.inuse.type_info)); the output likes this: pfn 5a4d0, mfn 5a4d0, p2mt 1 nl1e.l1 800000005a4d0063 page count 80000002, marked count 2, page typeinfo 74000001 When I allocate memory using vmalloc the output likes this: pfn 351ed, mfn 351ed, p2mt 1 nl1e.l1 80000000351ed063 page count 80000003, marked count 3, page typeinfo 74000002 previously I think the referece number (count_info) of these new allocated buffers should be "1". Now the output confuses me. Any one can explain this? Thanks very much Yueqiang 2010-08-05 strongerwill _______________________________________________ Xen-devel mailing list Xen-devel@lists.xensource.com http://lists.xensource.com/xen-devel