Re: [PATCH] Fix packed-not-aligned error on GCC 8

[Michael Chang]

When building with GCC 8, there are several errors regarding packed-not-aligned.

./include/grub/gpt_partition.h:79:1: error: alignment 1 of ‘struct 
grub_gpt_partentry’ is less than 8 [-Werror=packed-not-aligned]

This patch tries to fix the build error by cleaning up the ambiguity of placing
aligned structure in a packed one. In "struct grub_btrfs_time" and "struct
grub_gpt_part_type", the aligned attribute seems to be superfluous, and also
has to be packed, to ensure the structure is bit-to-bit mapped to the format
laid on disk. I think we could blame to copy and paste error here for the
mistake. In "struct efi_variable", we have to use grub_efi_packed_guid_t, as
the name suggests. :)

Signed-off-by: Michael Chang <address@hidden>
Tested-by: Michael Chang <address@hidden>

---
 grub-core/fs/btrfs.c          | 2 +-
 include/grub/efiemu/runtime.h | 2 +-
 include/grub/gpt_partition.h  | 2 +-
 3 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/grub-core/fs/btrfs.c b/grub-core/fs/btrfs.c
index 4849c1ceb..be195448d 100644
--- a/grub-core/fs/btrfs.c
+++ b/grub-core/fs/btrfs.c
@@ -175,7 +175,7 @@ struct grub_btrfs_time
 {
   grub_int64_t sec;
   grub_uint32_t nanosec;
-} __attribute__ ((aligned (4)));
+} GRUB_PACKED;
 
 struct grub_btrfs_inode
 {
diff --git a/include/grub/efiemu/runtime.h b/include/grub/efiemu/runtime.h
index 9b6b729f4..36d2dedf4 100644
--- a/include/grub/efiemu/runtime.h
+++ b/include/grub/efiemu/runtime.h
@@ -29,7 +29,7 @@ struct grub_efiemu_ptv_rel
 
 struct efi_variable
 {
-  grub_efi_guid_t guid;
+  grub_efi_packed_guid_t guid;
   grub_uint32_t namelen;
   grub_uint32_t size;
   grub_efi_uint32_t attributes;
diff --git a/include/grub/gpt_partition.h b/include/grub/gpt_partition.h
index 1b32f6725..9668a68c3 100644
--- a/include/grub/gpt_partition.h
+++ b/include/grub/gpt_partition.h
@@ -28,7 +28,7 @@ struct grub_gpt_part_type
   grub_uint16_t data2;
   grub_uint16_t data3;
   grub_uint8_t data4[8];
-} __attribute__ ((aligned(8)));
+} GRUB_PACKED;
 typedef struct grub_gpt_part_type grub_gpt_part_type_t;
 
 #define GRUB_GPT_PARTITION_TYPE_EMPTY \
-- 
2.13.6