Hi
How can I get physics address from a virtual address in kernel space? For low mem I can simply use virt_to_phys macro, and for those memory been mapped by ioremap, I try to walk through the pagetable by following code on arm platform:
static unsigned long himem_virt_to_phys(unsigned long virt) {
pmd_t * pmd; pte_t * pte; unsigned long phys_addr;
pmd = ( pmd_t * ) (pgd_offset_k(virt));
pte = pte_offset_kernel(pmd, virt & ~PGDIR_MASK);
phys_addr = ( pte_val(*pte) & PAGE_MASK ) | ( virt & ~PAGE_MASK);
printk("--- pmd addr = %lx, pte addr = %lx \n",pmd,pte); printk("--- pte content = %lx\n",pte_val(*pte)); printk("------ virt = %lx, phys= %lx \n",virt, phys_addr);
return phys_addr;
}
it did work, but when I try to get the physical address of a local var say i, it won't work! Why ? Is there some thing I missing?
the code i test the func is as following:
//--------------------- int i;
unsigned long virt;
virt = (unsigned long)ioremap(0x10018000,0x10000);
himem_virt_to_phys(virt);
i = 28; printk("&i = %x\n", &i); himem_virt_to_phys((unsigned long)&i);
//---------------------
and the outcome:
--- pmd addr = c0007120, pte addr = c3fdba9c
--- pte content = 100180a3
------ virt = c48a7000, phys= 10018000
&i = c3d99f64
--- pmd addr = c00070f0, pte addr = c3c00e64
--- pte content = e51b5084
------ virt = c3d99f64, phys= e51b5f64
this is not right , since pte's last bit is not 1 , and actually my sdram mem is on 0x1xxxxxxx not 0xExxxxxxx
Any ideas ? Thx