in OS kernel code, a physical address is uint64, but it is often being cast as a void, or char, then carry around. I think this makes a lot of interface like memset, memcpy, etc more convenient to use.
void vmprint_helper(pagetable_t *pagetable*, char* prefix, int level) {
// there are 2^9 = 512 PTEs in a page table.
for(int k = 0; k < 512; k++) {
pte_t pte = pagetable[k];
if(pte & PTE_V) {
printf(“%s%d: pte %p pa %p\n”, prefix, k, pte, PTE2PA(pte));
int next_level = level - 1;
if (level > 0) {
uint64 child = PTE2PA(pte);
pagetable_t pt = (pagetable_t)child;
vmprint_helper(pt, print_prefix(next_level), next_level);
}
}
}
}
void vmprint(pagetable_t *pagetable*)
{
printf(“page table %p\n”, pagetable);
vmprint_helper(pagetable, “..”, 2);
}
page table 0x0000000087f6e000
..0: pte 0x0000000021fda801 pa 0x0000000087f6a000
....0: pte 0x0000000021fda401 pa 0x0000000087f69000
......0: pte 0x0000000021fdac1f pa 0x0000000087f6b000
......1: pte 0x0000000021fda00f pa 0x0000000087f68000
......2: pte 0x0000000021fd9c1f pa 0x0000000087f67000
..255: pte 0x0000000021fdb401 pa 0x0000000087f6d000
....511: pte 0x0000000021fdb001 pa 0x0000000087f6c000
......510: pte 0x0000000021fdd807 pa 0x0000000087f76000
......511: pte 0x000000002000200b pa 0x0000000080008000
init: starting sh
page table 0x0000000087f63000
..0: pte 0x0000000021fd7c01 pa 0x0000000087f5f000
....0: pte 0x0000000021fd7801 pa 0x0000000087f5e000
......0: pte 0x0000000021fd801f pa 0x0000000087f60000
......1: pte 0x0000000021fd741f pa 0x0000000087f5d000
......2: pte 0x0000000021fd700f pa 0x0000000087f5c000
......3: pte 0x0000000021fd6c1f pa 0x0000000087f5b000
..255: pte 0x0000000021fd8801 pa 0x0000000087f62000
....511: pte 0x0000000021fd8401 pa 0x0000000087f61000
......510: pte 0x0000000021fdbc07 pa 0x0000000087f6f000
......511: pte 0x000000002000200b pa 0x0000000080008000
Another reason cast uint64 to void* is easy to print. (see above code about how to print page tables)