On Tue, Apr 09, 2019 at 08:57:25PM +1000, Vladimir 'phcoder' Serbinenko wrote: > On Tue, Apr 9, 2019 at 8:48 PM Michael Chang <mch...@suse.com> wrote: > > > > This patch set attempts to resolve the build failure in openSUSE build > > service equipped with new gcc 9 compiler, which has added a new warning > > flag -Waddress-of-packed-member. > > > > The new warning performs the check for taking the address of packed > > member directly to a pointer variable with higher alignment requirement > > and the outcome is risky to memory alignment fault on some architecture > > when deferencing it. > The problem here is that there is no way to tell the compiler to > create a structure without padding but a pointer to which is aligned. > This is very common in GRUB. Consider a struct like following: > grub_uint16_t a; > grub_uint32_t b; > grub_uint16_t c[40]; > > This needs packed attribute as otherwise compiler will insert a > padding before b. Yet c is guaranteed to be aligned if the pointer to > the structure is aligned.
But sometimes it is not easy to know as the packed structure could be embedded to another and also it could map to a specific portion in memory read from a file, with no guarantee where will be started (for eg via searching occurrence of specific magic number ..) Thanks, Michael > > > > Please help to review. > > > > Thanks. > > > > Michael Chang (8): > > cpio: fix gcc9 error address-of-packed-member > > jfs: fix gcc9 error address-of-packed-member > > hfs: fix gcc9 error address-of-packed-member > > hfsplus: fix gcc9 error address-of-packed-member > > acpi: fix gcc9 error address-of-packed-member > > usbtest: fix gcc9 error address-of-packed-member > > chainloader: fix gcc9 error address-of-packed-member > > efi: fix gcc9 error address-of-packed-member > > > > grub-core/commands/usbtest.c | 13 ++++++++- > > grub-core/fs/cpio.c | 5 ++-- > > grub-core/fs/cpio_be.c | 5 ++-- > > grub-core/fs/hfsplus.c | 57 > > ++++++++++++++++++++++++++------------ > > grub-core/fs/jfs.c | 5 ++-- > > grub-core/kern/efi/efi.c | 27 ++++++++++++++++-- > > grub-core/loader/efi/chainloader.c | 12 ++++++-- > > include/grub/acpi.h | 2 +- > > include/grub/hfs.h | 2 +- > > 9 files changed, 96 insertions(+), 32 deletions(-) > > > > -- > > 2.16.4 > > > > > > _______________________________________________ > > Grub-devel mailing list > > Grub-devel@gnu.org > > https://lists.gnu.org/mailman/listinfo/grub-devel > > > > -- > Regards > Vladimir 'phcoder' Serbinenko > > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel > _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
