By default SeaBIOS can map up to 2 hard disks, and more hard disks beyond
2 will be rejected. This restriction is caused by limited BDA slots.
This patch added support for mapping more than 2 hard disks by dynamically
mapping the hard disk right before we're about to boot the hard disk.
Signed-off-by: Bin Gao <gao...@amazon.com>
---
src/Kconfig | 8 ++++++++
src/block.c | 17 ++++++++++++++++-
src/boot.c | 14 +++++++++++---
3 files changed, 35 insertions(+), 4 deletions(-)
diff --git a/src/Kconfig b/src/Kconfig
index 3a8ffa1..d6031e2 100644
--- a/src/Kconfig
+++ b/src/Kconfig
@@ -380,6 +380,14 @@ menu "BIOS interfaces"
help
Support int13 disk/floppy drive functions.
+ config DYNAMIC_MAP_HD
+ depends on DRIVES
+ bool "Dynamically map hard drives"
+ default n
+ help
+ Support dynamically map hard drives so that the boot logic can
+ support more than 2 hard drives.
+
config CDROM_BOOT
depends on DRIVES
bool "DVD/CDROM booting"
diff --git a/src/block.c b/src/block.c
index 1f600b8..904e5f4 100644
--- a/src/block.c
+++ b/src/block.c
@@ -253,6 +253,10 @@ add_drive(struct drive_s **idmap, u8 *count, struct
drive_s *drive)
}
// Map a hard drive
+//
+// By default SeaBIOS can map up to 2 hard disks, and more hard disks beyond
+// 2 will be rejected. This restriction is caused by limited BDA slots.
+// To support more than 2 hard drives, we need to enable CONFIG_DYNAMIC_MAP_HD.
void
map_hd_drive(struct drive_s *drive)
{
@@ -260,7 +264,18 @@ map_hd_drive(struct drive_s *drive)
struct bios_data_area_s *bda = MAKE_FLATPTR(SEG_BDA, 0);
int hdid = bda->hdcount;
dprintf(3, "Mapping hd drive %p to %d\n", drive, hdid);
- add_drive(IDMap[EXTTYPE_HD], &bda->hdcount, drive);
+ // To implement dynamic hard drive maping, we constantly keep
+ // bda->hdcount = 1, and use hdid = 0 all the times.
+ // map_hd_drive() must be called each time before boot to a
+ // specific hard drive.
+ if (CONFIG_DYNAMIC_MAP_HD) {
+ hdid = 0; // 0 - always the first hard drive
+ u8 tmp = 0;
+ add_drive(IDMap[EXTTYPE_HD], &tmp, drive);
+ bda->hdcount = 1;
+ } else {
+ add_drive(IDMap[EXTTYPE_HD], &bda->hdcount, drive);
+ }
// Setup disk geometry translation.
setup_translation(drive);
diff --git a/src/boot.c b/src/boot.c
index 1effd80..2e6e356 100644
--- a/src/boot.c
+++ b/src/boot.c
@@ -802,7 +802,7 @@ static int HaveHDBoot, HaveFDBoot;
static void
add_bev(int type, u32 vector)
{
- if (type == IPL_TYPE_HARDDISK && HaveHDBoot++)
+ if (type == IPL_TYPE_HARDDISK && HaveHDBoot++ && !CONFIG_DYNAMIC_MAP_HD)
return;
if (type == IPL_TYPE_FLOPPY && HaveFDBoot++)
return;
@@ -837,8 +837,14 @@ bcv_prepboot(void)
add_bev(IPL_TYPE_FLOPPY, 0);
break;
case IPL_TYPE_HARDDISK:
- map_hd_drive(pos->drive);
- add_bev(IPL_TYPE_HARDDISK, 0);
+ if (CONFIG_DYNAMIC_MAP_HD) {
+ // Pass the drive_s pointer to bev_s struct so that
+ // we can do dynamic hard disk map in do_boot().
+ add_bev(IPL_TYPE_HARDDISK, (u32)pos->drive);
+ } else {
+ map_hd_drive(pos->drive);
+ add_bev(IPL_TYPE_HARDDISK, 0);
+ }
break;
case IPL_TYPE_CDROM:
map_cd_drive(pos->drive);
@@ -998,6 +1004,8 @@ do_boot(int seq_nr)
break;
case IPL_TYPE_HARDDISK:
printf("Booting from Hard Disk...\n");
+ if (CONFIG_DYNAMIC_MAP_HD)
+ map_hd_drive((struct drive_s *)ie->vector);
boot_disk(0x80, 1);
break;
case IPL_TYPE_CDROM:
--
2.17.1
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