Make uboot_devdesc properly alias disk_devdesc, so that parsing the u-boot

loaderdev variable works correctly.

The uboot_devdesc struct is variously cast back and forth between
uboot_devdesc and disk_devdesc as pointers are handed off through various
opaque interfaces.  uboot_devdesc attempted to mimic the layout of
disk_devdesc by having a devdesc struct, followed by a union of some
device-specific stuff that included a struct that contains the same fields
as a disk_devdesc.  However, one of those fields inside the struct is 64-bit
which causes the entire union to be 64-bit aligned -- 32 bits of padding
is added between the struct devdesc and the union, so the whole mess ends
up NOT properly mimicking a disk_devdesc after all.  (In disk_devdesc there
is also 32 bits of padding, but it shows up immediately before the d_offset
field, rather than before the whole collection of d_* fields.)

This fixes the problem by using an anonymous union to overlay the devdesc
field uboot network devices need with the disk_devdesc that uboot storage
devices need.  This is a different solution than the one contributed with
the PR (so if anything goes wrong, the blame goes to me), but 95% of the
credit for this fix goes to Pawel Worach and Manuel Stuhn who analyzed the
problem and proposed a fix.

PR:		233097

2 files changed, 11 insertions, 15 deletions

diff --git a/stand/uboot/common/main.c b/stand/uboot/common/main.c
index 50a12cd425fb0..b1534b00d2683 100644
--- a/stand/uboot/common/main.c
+++ b/stand/uboot/common/main.c
@@ -310,13 +310,13 @@ print_disk_probe_info()
 	char slice[32];
 	char partition[32];
 
-	if (currdev.d_disk.slice > 0)
-		sprintf(slice, "%d", currdev.d_disk.slice);
+	if (currdev.d_disk.d_slice > 0)
+		sprintf(slice, "%d", currdev.d_disk.d_slice);
 	else
 		strcpy(slice, "<auto>");
 
-	if (currdev.d_disk.partition >= 0)
-		sprintf(partition, "%d", currdev.d_disk.partition);
+	if (currdev.d_disk.d_partition >= 0)
+		sprintf(partition, "%d", currdev.d_disk.d_partition);
 	else
 		strcpy(partition, "<auto>");
 
@@ -332,8 +332,8 @@ probe_disks(int devidx, int load_type, int load_unit, int load_slice,
 	int open_result, unit;
 	struct open_file f;
 
-	currdev.d_disk.slice = load_slice;
-	currdev.d_disk.partition = load_partition;
+	currdev.d_disk.d_slice = load_slice;
+	currdev.d_disk.d_partition = load_partition;
 
 	f.f_devdata = &currdev;
 	open_result = -1;
diff --git a/stand/uboot/lib/libuboot.h b/stand/uboot/lib/libuboot.h
index 8b81486b1fae9..59438e711a652 100644
--- a/stand/uboot/lib/libuboot.h
+++ b/stand/uboot/lib/libuboot.h
@@ -27,19 +27,15 @@
  * $FreeBSD$
  */
 
+#include <disk.h>
+
 struct uboot_devdesc {
-	struct devdesc		dd;	/* Must be first. */
 	union {
-		struct {
-			int	slice;
-			int	partition;
-			off_t	offset;
-		} disk;
-	} d_kind;
+		struct devdesc      dd;
+		struct disk_devdesc d_disk;
+	};
 };
 
-#define d_disk d_kind.disk
-
 /*
  * Default network packet alignment in memory.  On arm arches packets must be
  * aligned to cacheline boundaries.