Hi, Le Tue, 22 Jan 2008 16:15:49 +0530, Shreyansh <shreyansh.jain@xxxxxxxxx> a écrit : > (This is a x86_64 machine I am working on, running SLES10 SP1) I don't have the source code for that exact kernel version, and several things have changed since then. > 1) What does the instruction "mov 0xffffffff803d54e0(,%rax,8), > %rdx" imply? Your code is: 0xffffffff8012128e <page_to_pfn>: mov (%rdi),%rax 0xffffffff80121291 <page_to_pfn+3>: shr $0x38,%rax 0xffffffff80121295 <page_to_pfn+7>: mov 0xffffffff803d54e0(,%rax,8),%rdx 0xffffffff8012129d <page_to_pfn+15>: mov $0x6db6db6db6db6db7,%rax 0xffffffff801212a7 <page_to_pfn+25>: sub 0x620(%rdx),%rdi I suspect that the argument "struct page *" is passed in %rdi. It first dereferences it to get the page->flags value (which is at the beginning of the page structure). Once this value is in %rax, it shifts it right by 38 bits, which I suspect is the >> ZONETABLE_PGSHIFT in your source code. Then, it accesses to the zone_table[] array : it access to the %rax-th entry, in an array of elements with an 8 byte size (and zone_table[] is an array of "struct zone *", so it's an array of 8 bytes elements). In %rdx, we now have a pointer to a "struct zone *"... which in fact happens to be NULL. So, I would say that either your page->flags are broken, either your zone_table[] array is incorrect. > 2) for "RIP: 0010:[<ffffffff801212a7>] " what does > "0010" mean? It's the segment selector. It selects through which segment we are accessing the code. It is an offset in the Global Descriptor Table (GDT). These are x86/x86_64 specific bits, I don't think you care about this for your particular issue. > 3) Does "EFLAGS: 00010217" signify any error value, and > if it does, how to interpret it? Take the Intel Developer manual, volume 1 (available at http://www.intel.com/products/processor/manuals/), page 78. It describes the contents of the EFLAGS register. Sincerly, Thomas -- Thomas Petazzoni, Free Electrons Free Embedded Linux Training Materials on http://free-electrons.com/training (More than 1500 pages!)
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