trunc_batc
#define round_batc(a) trunc_batc((a) + BATC_BLKBYTES - 1)
e_data = trunc_batc((paddr_t)&end);
var = trunc_batc(va);
sz = round_batc(pa + sz) - trunc_batc(pa);
pa = trunc_batc(pa);
s_low = trunc_batc(s_text);