Support Windows NT 4

+ if (cylinders <= 1024 && cylinders <= 16 && sectors <= 63) {

The following patch allows the CVS version of qemu to install and boot Windows NT 4, as long as the `-isa' flag is used. Without the patch, trying to install NT 4 will fail because no hard disk will be detected. Almost unbelievably, NT 4 won't detect a hard drive unless the CMOS RAM says that it is there.

Even with this fix, WNT4 can't see the hard drives if PCI support is turned on. There must be something else to track down too.

It appears Windows NT 4 Workstation wants 122 Mb to install, but fails unless you give a 124 Mb image to qemu.
I tried successively 122 and 123 Mb and got everytime an error message saying the disk was too small.
(though the disk size was computed correctly)

Quoted 2 lines · --- Ben Pfaff

Even with this fix, WNT4 can't see the hard drives if PCI support is turned on. There must be something else to track down too.

The following patch allows the CVS version of qemu to install and boot Windows NT 4, as long as the `-isa' flag is used. Without the patch, trying to install NT 4 will fail because no hard disk will be detected. Almost unbelievably, NT 4 won't detect a hard drive unless the CMOS RAM says that it is there.

Even with this fix, WNT4 can't see the hard drives if PCI support is turned on. There must be something else to track down too.

Index: hw/ide.c
===================================================================
RCS file: /cvsroot/qemu/qemu/hw/ide.c,v
retrieving revision 1.26
diff -u -p -u -r1.26 ide.c

ide.c +1 -0

@@ -1875,6 +1875,7 @@ static void ide_init2(IDEState *ide_stat
                     s->heads = 16;
                     s->sectors = 63;
                 }
+                bdrv_set_geometry_hint(s->bs, s->cylinders, s->heads, s->sectors);
             }
             if (bdrv_get_type_hint(s->bs) == BDRV_TYPE_CDROM) {
                 s->is_cdrom = 1;

Index: hw/pc.c
===================================================================
RCS file: /cvsroot/qemu/qemu/hw/pc.c,v
retrieving revision 1.25
diff -u -p -u -r1.25 pc.c

pc.c +50 -2

@@ -101,13 +101,32 @@ static int cmos_get_fd_drive_type(int fd
     return val;
 }
 
-static void cmos_init(int ram_size, int boot_device)
+static void cmos_init_hd(int type_ofs, int info_ofs, BlockDriverState *hd) 
+{
+    RTCState *s = rtc_state;
+    int cylinders, heads, sectors;
+    bdrv_get_geometry_hint(hd, &cylinders, &heads, &sectors);
+    rtc_set_memory(s, type_ofs, 47);
+    rtc_set_memory(s, info_ofs, cylinders);
+    rtc_set_memory(s, info_ofs + 1, cylinders >> 8);
+    rtc_set_memory(s, info_ofs + 2, heads);
+    rtc_set_memory(s, info_ofs + 3, 0xff);
+    rtc_set_memory(s, info_ofs + 4, 0xff);
+    rtc_set_memory(s, info_ofs + 5, 0xc0 | ((heads > 8) << 3));
+    rtc_set_memory(s, info_ofs + 6, cylinders);
+    rtc_set_memory(s, info_ofs + 7, cylinders >> 8);
+    rtc_set_memory(s, info_ofs + 8, sectors);
+}
+
+/* hd_table must contain 4 block drivers */
+static void cmos_init(int ram_size, int boot_device, BlockDriverState **hd_table)
 {
     RTCState *s = rtc_state;
     int val;
     int fd0, fd1, nb;
     time_t ti;
     struct tm *tm;
+    int i;
 
     /* set the CMOS date */
     time(&ti);

@@ -187,6 +206,35 @@ static void cmos_init(int ram_size, int 
     val |= 0x04; /* PS/2 mouse installed */
     rtc_set_memory(s, REG_EQUIPMENT_BYTE, val);
 
+    /* hard drives */
+
+    rtc_set_memory(s, 0x12, (hd_table[0] ? 0xf0 : 0) | (hd_table[1] ? 0x0f : 0));
+    if (hd_table[0])
+        cmos_init_hd(0x19, 0x1b, hd_table[0]);
+    if (hd_table[1]) 
+        cmos_init_hd(0x1a, 0x24, hd_table[1]);
+
+    val = 0;
+    for (i = 0; i < 4; i++)
+        if (hd_table[i]) {
+            int cylinders, heads, sectors;
+            uint8_t translation;
+            
+            bdrv_get_geometry_hint(hd_table[i], &cylinders, &heads, &sectors);
+            if (cylinders <= 1024 && cylinders <= 16 && sectors <= 63) {
+                /* No translation. */
+                translation = 0;
+            } else if (cylinders * heads > 131072) {
+                /* LBA translation. */
+                translation = 1;
+            } else {
+                /* LARGE translation. */
+                translation = 2;
+            }
+
+            val |= translation << (i * 2);
+        }
+    rtc_set_memory(s, 0x39, val);
 }
 
 static void speaker_ioport_write(void *opaque, uint32_t addr, uint32_t val)

@@ -506,7 +554,7 @@ void pc_init(int ram_size, int vga_ram_s
 
     floppy_controller = fdctrl_init(6, 2, 0, 0x3f0, fd_table);
 
-    cmos_init(ram_size, boot_device);
+    cmos_init(ram_size, boot_device, bs_table);
 
     /* must be done after all PCI devices are instanciated */
     /* XXX: should be done in the Bochs BIOS */