[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>

3 files changed, 13 insertions, 36 deletions

diff --git a/src/net/tcp/httpblock.c b/src/net/tcp/httpblock.c
index e124ad2d..1abd6b34 100644
--- a/src/net/tcp/httpblock.c
+++ b/src/net/tcp/httpblock.c
@@ -114,21 +114,3 @@ int http_block_read_capacity ( struct http_transaction *http,
  err_open:
 	return rc;
 }
-
-/**
- * Describe device in ACPI table
- *
- * @v http		HTTP transaction
- * @v acpi		ACPI table
- * @v len		Length of ACPI table
- * @ret rc		Return status code
- */
-int http_acpi_describe ( struct http_transaction *http,
-			 struct acpi_description_header *acpi, size_t len ) {
-
-	DBGC ( http, "HTTP %p cannot yet describe device in an ACPI table\n",
-	       http );
-	( void ) acpi;
-	( void ) len;
-	return 0;
-}
diff --git a/src/net/tcp/httpcore.c b/src/net/tcp/httpcore.c
index ec527c64..ce53a212 100644
--- a/src/net/tcp/httpcore.c
+++ b/src/net/tcp/httpcore.c
@@ -509,28 +509,11 @@ __weak int http_block_read_capacity ( struct http_transaction *http __unused,
 	return -ENOTSUP;
 }
 
-/**
- * Describe device in ACPI table (when HTTP block device support is not present)
- *
- * @v http		HTTP transaction
- * @v acpi		ACPI table
- * @v len		Length of ACPI table
- * @ret rc		Return status code
- */
-__weak int http_acpi_describe ( struct http_transaction *http __unused,
-				struct acpi_description_header *acpi __unused,
-				size_t len __unused ) {
-
-	return -ENOTSUP;
-}
-
 /** HTTP data transfer interface operations */
 static struct interface_operation http_xfer_operations[] = {
 	INTF_OP ( block_read, struct http_transaction *, http_block_read ),
 	INTF_OP ( block_read_capacity, struct http_transaction *,
 		  http_block_read_capacity ),
-	INTF_OP ( acpi_describe, struct http_transaction *,
-		  http_acpi_describe ),
 	INTF_OP ( xfer_window_changed, struct http_transaction *, http_step ),
 	INTF_OP ( intf_close, struct http_transaction *, http_close ),
 };
diff --git a/src/net/tcp/iscsi.c b/src/net/tcp/iscsi.c
index 1e6fd1f5..7de4a7bf 100644
--- a/src/net/tcp/iscsi.c
+++ b/src/net/tcp/iscsi.c
@@ -1810,12 +1810,23 @@ static int iscsi_scsi_command ( struct iscsi_session *iscsi,
 	return iscsi->itt;
 }
 
+/**
+ * Get iSCSI ACPI descriptor
+ *
+ * @v iscsi		iSCSI session
+ * @ret desc		ACPI descriptor
+ */
+static struct acpi_descriptor * iscsi_describe ( struct iscsi_session *iscsi ) {
+
+	return &iscsi->desc;
+}
+
 /** iSCSI SCSI command-issuing interface operations */
 static struct interface_operation iscsi_control_op[] = {
 	INTF_OP ( scsi_command, struct iscsi_session *, iscsi_scsi_command ),
 	INTF_OP ( xfer_window, struct iscsi_session *, iscsi_scsi_window ),
 	INTF_OP ( intf_close, struct iscsi_session *, iscsi_close ),
-	INTF_OP ( acpi_describe, struct iscsi_session *, ibft_describe ),
+	INTF_OP ( acpi_describe, struct iscsi_session *, iscsi_describe ),
 };
 
 /** iSCSI SCSI command-issuing interface descriptor */
@@ -2064,6 +2075,7 @@ static int iscsi_open ( struct interface *parent, struct uri *uri ) {
 	intf_init ( &iscsi->socket, &iscsi_socket_desc, &iscsi->refcnt );
 	process_init_stopped ( &iscsi->process, &iscsi_process_desc,
 			       &iscsi->refcnt );
+	acpi_init ( &iscsi->desc, &ibft_model, &iscsi->refcnt );
 
 	/* Parse root path */
 	if ( ( rc = iscsi_parse_root_path ( iscsi, uri->opaque ) ) != 0 )