Hello Oren, Ah yes, absolutely right. I thought almost the same, just overlooked that pdp is right after pml4 in memory.
Oren thank you for help. 2015-02-03 18:42 GMT+06:00 Oren Twaig <[email protected]>: > Hi, > > This is the corresponding C code which can help you understand: > > u64 *pml4 = (u64*)pgtable; > u64 pdp = pgtable + 0x1000; > u64 pml4_entry = pdp | PTE_P | PTE_W | PTU; // present, write, userspace = > 0x7 > pml4[0] = pml4_entry; > > The 0x1007 you see is just the calculation of the pml4_entry. > > Oren Twaig. > > On 02/03/2015 02:25 PM, Alex Kuleshov wrote: >> Hello All, >> >> I have a question about page tables initialization in the >> arch/x86/boot/compressed/head_64.S >> >> After we clear memory for page tables, there is code which >> build PML4: >> >> leal pgtable + 0(%ebx), %edi >> leal 0x1007(%edi), %eax >> movl %eax, 0(%edi) >> >> Why there is offset 0x1007 instead just 0x7? 0x1007 is >> 4k + 7bit (PML4E) flags as i understand correctly. But >> why we skip first 4k here? >> >> Thank you. >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-kernel" in >> the body of a message to [email protected] >> More majordomo info at http://vger.kernel.org/majordomo-info.html >> Please read the FAQ at http://www.tux.org/lkml/ >> > > -- _________________________ 0xAX -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
