support T13 EDD3.0 spec

Some guests (such as Linux) expect BIOS to behave according to T13
EDD3.0 spec. T13 spec is much better then Phoenix since it provides
more information about interface and device paths. This patch adds
support for the spec. If guest provides buffer with enough space for
T13 EDD info return EDD according to T13 spec otherwise use Phoenix
one.

Signed-off-by: Gleb Natapov <gleb@redhat.com>
diff --git a/src/disk.c b/src/disk.c
index f7bfe9c..8f7c61f 100644
--- a/src/disk.c
+++ b/src/disk.c
@@ -503,6 +503,7 @@
 disk_1348(struct bregs *regs, struct drive_s *drive_g)
 {
     u16 size = GET_INT13DPT(regs, size);
+    u16 t13 = size == 74;
 
     // Buffer is too small
     if (size < 26) {
@@ -553,8 +554,9 @@
     // EDD 2.x
 
     int bdf;
-    u16 iobase1;
-    u64 device_path;
+    u16 iobase1 = 0;
+    u64 device_path = 0;
+    u8 channel = 0;
     SET_INT13DPT(regs, size, 30);
     if (type == DTYPE_ATA || type == DTYPE_ATAPI) {
         u16 ebda_seg = get_ebda_seg();
@@ -573,6 +575,7 @@
         iobase1 = GET_GLOBALFLAT(chan_gf->iobase1);
         bdf = GET_GLOBALFLAT(chan_gf->pci_bdf);
         device_path = slave;
+        channel = GET_GLOBALFLAT(chan_gf->chanid);
 
         u16 options = 0;
         if (type == DTYPE_ATA) {
@@ -613,8 +616,6 @@
         SET_INT13DPT(regs, dpte_segment, 0);
         SET_INT13DPT(regs, dpte_offset, 0);
         bdf = GET_GLOBAL(drive_g->cntl_id);
-        device_path = 0;
-        iobase1 = 0;
     }
 
     if (size < 66) {
@@ -624,7 +625,7 @@
 
     // EDD 3.x
     SET_INT13DPT(regs, key, 0xbedd);
-    SET_INT13DPT(regs, dpi_length, 36);
+    SET_INT13DPT(regs, dpi_length, t13 ? 44 : 36);
     SET_INT13DPT(regs, reserved1, 0);
     SET_INT13DPT(regs, reserved2, 0);
 
@@ -632,17 +633,20 @@
         SET_INT13DPT(regs, host_bus[0], 'P');
         SET_INT13DPT(regs, host_bus[1], 'C');
         SET_INT13DPT(regs, host_bus[2], 'I');
-        SET_INT13DPT(regs, host_bus[3], 0);
+        SET_INT13DPT(regs, host_bus[3], ' ');
 
         u32 path = (pci_bdf_to_bus(bdf) | (pci_bdf_to_dev(bdf) << 8)
                     | (pci_bdf_to_fn(bdf) << 16));
+        if (t13)
+            path |= channel << 24;
+
         SET_INT13DPT(regs, iface_path, path);
     } else {
         // ISA
         SET_INT13DPT(regs, host_bus[0], 'I');
         SET_INT13DPT(regs, host_bus[1], 'S');
         SET_INT13DPT(regs, host_bus[2], 'A');
-        SET_INT13DPT(regs, host_bus[3], 0);
+        SET_INT13DPT(regs, host_bus[3], ' ');
 
         SET_INT13DPT(regs, iface_path, iobase1);
     }
@@ -651,22 +655,30 @@
         SET_INT13DPT(regs, iface_type[0], 'A');
         SET_INT13DPT(regs, iface_type[1], 'T');
         SET_INT13DPT(regs, iface_type[2], 'A');
-        SET_INT13DPT(regs, iface_type[3], 0);
+        SET_INT13DPT(regs, iface_type[3], ' ');
     } else {
         SET_INT13DPT(regs, iface_type[0], 'S');
         SET_INT13DPT(regs, iface_type[1], 'C');
         SET_INT13DPT(regs, iface_type[2], 'S');
         SET_INT13DPT(regs, iface_type[3], 'I');
     }
-    SET_INT13DPT(regs, iface_type[4], 0);
-    SET_INT13DPT(regs, iface_type[5], 0);
-    SET_INT13DPT(regs, iface_type[6], 0);
-    SET_INT13DPT(regs, iface_type[7], 0);
+    SET_INT13DPT(regs, iface_type[4], ' ');
+    SET_INT13DPT(regs, iface_type[5], ' ');
+    SET_INT13DPT(regs, iface_type[6], ' ');
+    SET_INT13DPT(regs, iface_type[7], ' ');
 
-    SET_INT13DPT(regs, device_path, device_path);
+    if (t13) {
+        SET_INT13DPT(regs, t13.device_path[0], device_path);
+        SET_INT13DPT(regs, t13.device_path[1], 0);
 
-    SET_INT13DPT(regs, checksum
-                 , -checksum_far(regs->ds, (void*)(regs->si+30), 35));
+        SET_INT13DPT(regs, t13.checksum
+                     , -checksum_far(regs->ds, (void*)(regs->si+30), 43));
+    } else {
+        SET_INT13DPT(regs, phoenix.device_path, device_path);
+
+        SET_INT13DPT(regs, phoenix.checksum
+                     , -checksum_far(regs->ds, (void*)(regs->si+30), 35));
+    }
 
     disk_ret(regs, DISK_RET_SUCCESS);
 }
diff --git a/src/disk.h b/src/disk.h
index f31de73..10a0051 100644
--- a/src/disk.h
+++ b/src/disk.h
@@ -63,9 +63,18 @@
     u8  host_bus[4];
     u8  iface_type[8];
     u64 iface_path;
-    u64 device_path;
-    u8  reserved3;
-    u8  checksum;
+    union {
+        struct {
+            u64 device_path;
+            u8  reserved3;
+            u8  checksum;
+        } phoenix;
+        struct {
+            u64 device_path[2];
+            u8  reserved3;
+            u8  checksum;
+        } t13;
+    };
 } PACKED;
 
 #define GET_INT13DPT(regs,var)                                          \