xv6_rpi_port/uprogs/memlayout.h

// Memory layout

#define EXTMEM  0x8000    /* start of kernel code */
#define PHYSTOP         0x8000000  /* assuming 128M RAM; need a fix to find the true RAM size */
#define DEVSPACE        0xFE000000      /* i/o registers */

// Key addresses for address space layout (see kmap in vm.c for layout)
#define KERNBASE 0x80000000         // First kernel virtual address
#define KERNLINK (KERNBASE+EXTMEM)  // Address where kernel is linked
#define USERBOUND 0x40000000        // maximum user space due to one page pgd

#define MACHADDR        (KERNBASE+0x2000)
#define PA_START 0x0
#define PHYSIO          0x20000000
#define RAMSIZE         (128*MByte)
#define IOSIZE          (16*MByte)
#define TVSIZE          0x1000

static inline uint v2p(void *a) { return ((uint) (a))  - KERNBASE; }
static inline void *p2v(uint a) { return (void *) ((a) + KERNBASE); }

#define V2P(a) (((uint) (a)) - KERNBASE)
#define P2V(a) (((void *) (a)) + KERNBASE)

#define V2P_WO(x) ((x) - KERNBASE)    // same as V2P, but without casts
#define P2V_WO(x) ((x) + KERNBASE)    // same as V2P, but without casts