static int guess_disk_lchs(IDEState *s, int *pcylinders, int *pheads, int *psectors) { uint8_t *buf; int ret, i, heads, sectors, cylinders; struct partition *p; uint32_t nr_sects; buf = qemu_memalign(512, 512); if (buf == NULL) return -1; ret = bdrv_read(s->bs, 0, buf, 1); if (ret < 0) { qemu_free(buf); return -1; } /* test msdos magic */ if (buf[510] != 0x55 || buf[511] != 0xaa) { qemu_free(buf); return -1; } for(i = 0; i < 4; i++) { p = ((struct partition *)(buf + 0x1be)) + i; nr_sects = le32_to_cpu(p->nr_sects); if (nr_sects && p->end_head) { /* We make the assumption that the partition terminates on a cylinder boundary */ heads = p->end_head + 1; sectors = p->end_sector & 63; if (sectors == 0) continue; cylinders = s->nb_sectors / (heads * sectors); if (cylinders < 1 || cylinders > 16383) continue; *pheads = heads; *psectors = sectors; *pcylinders = cylinders; #if 0 printf("guessed geometry: LCHS=%d %d %d\n", cylinders, heads, sectors); #endif qemu_free(buf); return 0; } } qemu_free(buf); return -1; }