[SeaBIOS,v3,1/4] geometry: Read LCHS from fw_cfg

Commit Message

Sam Eiderman June 19, 2019, 9:23 a.m. UTC

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 lcyls lheads lsecs\n
    ...
    * device_path lcyls lheads lsecs\0

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 <[e-mail]>
Reviewed-by: Arbel Moshe <[e-mail]>
Signed-off-by: Sam Eiderman <[e-mail]>
---
 src/boot.c | 74 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 74 insertions(+)

Patch

diff --git a/src/boot.c b/src/boot.c
index 5acf94fe..a2cb167c 100644
--- a/src/boot.c
+++ b/src/boot.c
@@ -24,6 +24,79 @@ 
 
 
 /****************************************************************
+ * Boot device logical geometry
+ ****************************************************************/
+
+typedef struct BootDeviceLCHS {
+    char *name;
+    u32 lcyls;
+    u32 lheads;
+    u32 lsecs;
+} BootDeviceLCHS;
+
+static BootDeviceLCHS *BiosGeometry VARVERIFY32INIT;
+static int BiosGeometryCount;
+
+static char *
+parse_u32(char *cur, u32 *n)
+{
+    u32 m = 0;
+    if (cur) {
+        while ('0' <= *cur && *cur <= '9') {
+            m = 10 * m + (*cur - '0');
+            cur++;
+        }
+        if (*cur != '\0')
+            cur++;
+    }
+    *n = m;
+    return cur;
+}
+
+static void
+loadBiosGeometry(void)
+{
+    char *f = romfile_loadfile("bios-geometry", NULL);
+    if (!f)
+        return;
+
+    int i = 0;
+    BiosGeometryCount = 1;
+    while (f[i]) {
+        if (f[i] == '\n')
+            BiosGeometryCount++;
+        i++;
+    }
+    BiosGeometry = malloc_tmphigh(BiosGeometryCount * sizeof(BootDeviceLCHS));
+    if (!BiosGeometry) {
+        warn_noalloc();
+        free(f);
+        BiosGeometryCount = 0;
+        return;
+    }
+
+    dprintf(1, "bios geometry:\n");
+    i = 0;
+    do {
+        BootDeviceLCHS *d = &BiosGeometry[i];
+        d->name = f;
+        f = strchr(f, '\n');
+        if (f)
+            *(f++) = '\0';
+        char *chs_values = strchr(d->name, ' ');
+        if (chs_values)
+            *(chs_values++) = '\0';
+        chs_values = parse_u32(chs_values, &d->lcyls);
+        chs_values = parse_u32(chs_values, &d->lheads);
+        chs_values = parse_u32(chs_values, &d->lsecs);
+        dprintf(1, "%s: (%u, %u, %u)\n",
+                d->name, d->lcyls, d->lheads, d->lsecs);
+        i++;
+    } while (f);
+}
+
+
+/****************************************************************
  * Boot priority ordering
  ****************************************************************/
 
@@ -288,6 +361,7 @@  boot_init(void)
     BootRetryTime = romfile_loadint("etc/boot-fail-wait", 60*1000);
 
     loadBootOrder();
+    loadBiosGeometry();
 }