[block] Describe all SAN devices via ACPI tables

Describe all SAN devices via ACPI tables such as the iBFT.  For tables
that can describe only a single device (i.e. the aBFT and sBFT), one
table is installed per device.  For multi-device tables (i.e. the
iBFT), all devices are described in a single table.

An underlying SAN device connection may be closed at the time that we
need to construct an ACPI table.  We therefore introduce the concept
of an "ACPI descriptor" which enables the SAN boot code to maintain an
opaque pointer to the underlying object, and an "ACPI model" which can
build tables from a list of such descriptors.  This separates the
lifecycles of ACPI descriptions from the lifecycles of the block
device interfaces, and allows for construction of the ACPI tables even
if the block device interface has been closed.

For a multipath SAN device, iPXE will wait until sufficient
information is available to describe all devices but will not wait for
all paths to connect successfully.  For example: with a multipath
iSCSI boot iPXE will wait until at least one path has become available
and name resolution has completed on all other paths.  We do this
since the iBFT has to include IP addresses rather than DNS names.  We
will commence booting without waiting for the inactive paths to either
become available or close; this avoids unnecessary boot delays.

Note that the Linux kernel will refuse to accept an iBFT with more
than two NIC or target structures.  We therefore describe only the
NICs that are actually required in order to reach the described
targets.  Any iBFT with at most two targets is therefore guaranteed to
describe at most two NICs.

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

1 files changed, 21 insertions, 15 deletions

diff --git a/src/include/ipxe/ibft.h b/src/include/ipxe/ibft.h
index 35f15105c..51ce781a6 100644
--- a/src/include/ipxe/ibft.h
+++ b/src/include/ipxe/ibft.h
@@ -49,6 +49,9 @@ FILE_LICENCE ( BSD2 );
 /** iSCSI Boot Firmware Table signature */
 #define IBFT_SIG ACPI_SIGNATURE ( 'i', 'B', 'F', 'T' )
 
+/** Alignment of structures within iBFT */
+#define IBFT_ALIGN 16
+
 /** An offset from the start of the iBFT */
 typedef uint16_t ibft_off_t;
 
@@ -98,6 +101,20 @@ struct ibft_header {
 } __attribute__ (( packed ));
 
 /**
+ * iBFT NIC and Target offset pair
+ *
+ * There is no implicit relation between the NIC and the Target, but
+ * using this structure simplifies the table construction code while
+ * matching the expected table layout.
+ */
+struct ibft_offset_pair {
+	/** Offset to NIC structure */
+	ibft_off_t nic;
+	/** Offset to Target structure */
+	ibft_off_t target;
+} __attribute__ (( packed ));
+
+/**
  * iBFT Control structure
  *
  */
@@ -108,14 +125,8 @@ struct ibft_control {
 	uint16_t extensions;
 	/** Offset to Initiator structure */
 	ibft_off_t initiator;
-	/** Offset to NIC structure for NIC 0 */
-	ibft_off_t nic_0;
-	/** Offset to Target structure for target 0 */
-	ibft_off_t target_0;
-	/** Offset to NIC structure for NIC 1 */
-	ibft_off_t nic_1;
-	/** Offset to Target structure for target 1 */
-	ibft_off_t target_1;
+	/** Offsets to NIC and Target structures */
+	struct ibft_offset_pair pair[2];
 } __attribute__ (( packed ));
 
 /** Structure ID for Control section */
@@ -262,18 +273,13 @@ struct ibft_target {
  */
 struct ibft_table {
 	/** ACPI header */
-	struct acpi_description_header acpi;
+	struct acpi_header acpi;
 	/** Reserved */
 	uint8_t reserved[12];
 	/** Control structure */
 	struct ibft_control control;
 } __attribute__ (( packed ));
 
-struct iscsi_session;
-struct net_device;
-
-extern int ibft_describe ( struct iscsi_session *iscsi,
-			   struct acpi_description_header *acpi,
-			   size_t len );
+extern struct acpi_model ibft_model __acpi_model;
 
 #endif /* _IPXE_IBFT_H */