drivers/disk: Optical volume detection without writes on BIOS
diff --git a/common/drivers/disk.s2.c b/common/drivers/disk.s2.c
index 4d8a286d..055342cd 100644
--- a/common/drivers/disk.s2.c
+++ b/common/drivers/disk.s2.c
@@ -141,39 +141,6 @@ int disk_read_sectors(struct volume *volume, void *buf, uint64_t block, size_t c
return DISK_SUCCESS;
}
-static int disk_write_sectors(struct volume *volume, void *buf, uint64_t block, size_t count) {
- struct dap dap = {0};
-
- if (count * volume->sector_size > XFER_BUF_SIZE)
- panic(false, "XFER");
-
- if (xfer_buf == NULL)
- xfer_buf = conv_mem_alloc(XFER_BUF_SIZE);
-
- dap.size = 16;
- dap.count = count;
- dap.segment = rm_seg(xfer_buf);
- dap.offset = rm_off(xfer_buf);
- dap.lba = block;
-
- struct rm_regs r = {0};
- r.eax = 0x4301;
- r.edx = volume->drive;
- r.esi = (uint32_t)rm_off(&dap);
- r.ds = rm_seg(&dap);
-
- if (buf != NULL)
- memcpy(xfer_buf, buf, count * volume->sector_size);
-
- rm_int(0x13, &r, &r);
-
- if (r.eflags & EFLAGS_CF) {
- return DISK_FAILURE;
- }
-
- return DISK_SUCCESS;
-}
-
static bool detect_sector_size(struct volume *volume) {
struct dap dap = {0};
@@ -311,11 +278,9 @@ void disk_create_index(void) {
continue;
}
- if (disk_read_sectors(block, xfer_buf, 0, 1) != DISK_SUCCESS) {
- continue;
- }
-
- block->is_optical = (disk_write_sectors(block, xfer_buf, 0, 1) != DISK_SUCCESS) && block->sector_size == 2048;
+ // Detect optical drives via DPTE ATAPI bit (bit 6) or sector size heuristic
+ bool is_atapi = (dpte != NULL && (dpte->flags & (1 << 6)));
+ block->is_optical = is_atapi || (block->sector_size == 2048 && is_removable);
if (!is_removable && !block->is_optical) {
if (consumed_bda_disks == bda_disk_count) {
