[SeaBIOS] [PATCH v2 1/5] geometry: Read LCHS from fw_cfg

[Sam Eiderman]

Read bios geometry for boot devices from fw_cfg.

By receiving LCHS values directly from QEMU through fw_cfg we will be
able to support logical geometries which can not be inferred by SeaBIOS
itself.
(For instance: A 8GB virtio-blk hard drive which was originally created
as an IDE and must report LCHS of */32/63 for its operating system to
function will always break under SeaBIOS since a LARGE/LBA translation
will be used, causing the number of reported logical heads to be > 32.)

The only LCHS paravirtual interface available at the moment is for IDE
disks (rtc_read() in get_translation()) and it's limited to a maximum
of 4 disks (this code existed in SeaBIOS's translation function before
SCSI and VirtIO were even introduced).
This is why we create a new interface which allows passing LCHS
information per hdd.

Boot device information is serialized in the following way:
    * device path (sz string)
    * device lchs
    ...
    * device path (sz string)
    * device lchs

Device path is a null terminated string in the "Open Firmware" device
path format, the same path as used in bootorder.

Reviewed-by: Karl Heubaum 
Reviewed-by: Arbel Moshe 
Signed-off-by: Sam Eiderman 
---
 src/boot.c | 79 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)

diff --git a/src/boot.c b/src/boot.c
index 5acf94fe..b4382041 100644
--- a/src/boot.c
+++ b/src/boot.c
@@ -24,6 +24,84 @@

/****************************************************************
+ * Boot device logical geometry
+ ****************************************************************/
+
+typedef struct BootDeviceLCHSSerialized {
+    u32 lcyls;
+    u32 lheads;
+    u32 lsecs;
+} PACKED BootDeviceLCHSSerialized;
+
+typedef struct BootDeviceLCHS {
+    char *name;
+    u32 lcyls;
+    u32 lheads;
+    u32 lsecs;
+} BootDeviceLCHS;
+
+static BootDeviceLCHS *BiosGeometry VARVERIFY32INIT;
+static int BiosGeometryCount;
+
+static void
+loadBiosGeometry(void)
+{
+    BiosGeometryCount = 0;
+    int fsize;
+    char *f = romfile_loadfile("bios-geometry", &fsize);
+    if (!f)
+        return;
+
+    u32 struct_size = sizeof(BootDeviceLCHSSerialized);
+
+    int i;
+    int str_found = 0;
+
+    for (i = 0; i < fsize; i++) {
+        if (f[i] != '\0')
+            str_found = 1;
+        else if (f[i] == '\0' && str_found) {
+            str_found = 0;
+            i++;
+            if (i + struct_size > fsize)
+                break;
+            i += struct_size - 1;
+            BiosGeometryCount++;
+        } else
+            break;
+    }
+
+    BiosGeometry = malloc_tmphigh(BiosGeometryCount * sizeof(BootDeviceLCHS));
+    if (!BiosGeometry) {
+        warn_noalloc();
+        free(f);
+        BiosGeometryCount = 0;
+        return;
+    }
+
+    dprintf(1, "bios geometry:\n");
+
+    BootDeviceLCHSSerialized *blk;
+    BootDeviceLCHS *d;
+
+    for (i = 0; i < BiosGeometryCount; i++) {
+        d = &BiosGeometry[i];
+        d->name = f;
+        f += strlen(f) + 1;
+
+        blk = (BootDeviceLCHSSerialized *)f;
+        d->lcyls = blk->lcyls;
+        d->lheads = blk->lheads;
+        d->lsecs = blk->lsecs;
+        f += struct_size;
+
+        dprintf(1, "%s: (%u, %u, %u)\n",
+                d->name, d->lcyls, d->lheads, d->lsecs);
+    }
+}
+
+
+/****************************************************************
  * Boot priority ordering
  ****************************************************************/

@@ -288,6 +366,7 @@ boot_init(void)
     BootRetryTime = romfile_loadint("etc/boot-fail-wait", 60*1000);

loadBootOrder();
+    loadBiosGeometry();
 }