[block] Centralise "san-drive" setting

The concept of the SAN drive number is meaningful only in a BIOS
environment, where it represents the INT13 drive number (0x80 for the
first hard disk).  We retain this concept in a UEFI environment to
allow for a simple way for iPXE commands to refer to SAN drives.

Centralise the concept of the default drive number, since it is shared
between all supported environments.

Signed-off-by: Michael Brown <mcb30@ipxe.org>

2 files changed, 39 insertions, 1 deletions

diff --git a/src/core/null_sanboot.c b/src/core/null_sanboot.c
index 2f7522c6..31a8a56b 100644
--- a/src/core/null_sanboot.c
+++ b/src/core/null_sanboot.c
@@ -43,7 +43,6 @@ static int null_san_describe ( unsigned int drive __unused ) {
 	return -EOPNOTSUPP;
 }
 
-PROVIDE_SANBOOT_INLINE ( null, san_default_drive );
 PROVIDE_SANBOOT ( null, san_hook, null_san_hook );
 PROVIDE_SANBOOT ( null, san_unhook, null_san_unhook );
 PROVIDE_SANBOOT ( null, san_boot, null_san_boot );
diff --git a/src/core/sanboot.c b/src/core/sanboot.c
index da1b68b5..42a30839 100644
--- a/src/core/sanboot.c
+++ b/src/core/sanboot.c
@@ -39,9 +39,21 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #include <ipxe/timer.h>
 #include <ipxe/process.h>
 #include <ipxe/iso9660.h>
+#include <ipxe/dhcp.h>
+#include <ipxe/settings.h>
 #include <ipxe/sanboot.h>
 
 /**
+ * Default SAN drive number
+ *
+ * The drive number is a meaningful concept only in a BIOS
+ * environment, where it represents the INT13 drive number (0x80 for
+ * the first hard disk).  We retain it in other environments to allow
+ * for a simple way for iPXE commands to refer to SAN drives.
+ */
+#define SAN_DEFAULT_DRIVE 0x80
+
+/**
  * Timeout for block device commands (in ticks)
  *
  * Underlying devices should ideally never become totally stuck.
@@ -541,6 +553,7 @@ int register_sandev ( struct san_device *sandev ) {
 
 	/* Add to list of SAN devices */
 	list_add_tail ( &sandev->list, &san_devices );
+	DBGC ( sandev, "SAN %#02x registered\n", sandev->drive );
 
 	return 0;
 }
@@ -560,4 +573,30 @@ void unregister_sandev ( struct san_device *sandev ) {
 
 	/* Remove from list of SAN devices */
 	list_del ( &sandev->list );
+	DBGC ( sandev, "SAN %#02x unregistered\n", sandev->drive );
+}
+
+/** The "san-drive" setting */
+const struct setting san_drive_setting __setting ( SETTING_SANBOOT_EXTRA,
+						   san-drive ) = {
+	.name = "san-drive",
+	.description = "SAN drive number",
+	.tag = DHCP_EB_SAN_DRIVE,
+	.type = &setting_type_uint8,
+};
+
+/**
+ * Get default SAN drive number
+ *
+ * @ret drive		Default drive number
+ */
+unsigned int san_default_drive ( void ) {
+	unsigned long drive;
+
+	/* Use "san-drive" setting, if specified */
+	if ( fetch_uint_setting ( NULL, &san_drive_setting, &drive ) >= 0 )
+		return drive;
+
+	/* Otherwise, default to booting from first hard disk */
+	return SAN_DEFAULT_DRIVE;
 }