On Fri, May 08, 2020 at 06:50:49AM +0200, Hans Ulrich Niedermann wrote: > Properly align all Multiboot2 header tags to 8 byte > boundaries as per the Multiboot2 specification. > > Note that the assembler directive ".align 8" is machine > dependent: On i386, it means "align to 8 byte boundary". > On mips, it means that the lower 8 bits of address must > be zero, i.e. ".align 8" aligns to a 256 byte boundary! > > Therefore, this changes boot_mips.S to use ".balign 8" > where it had mistakenly used ".align 8" before. > > The boot_i386.S file keeps using ".align 8".
I would use ".balign 8" everywhere to avoid confusion. > Note also that the Multiboot2 header termination tag > (unfortunately unlabeled in the source) actually needs > that extra alignment to an 8 byte boundary, as the > preceding tag (framebuffer_tag_start) is 20 bytes long > which is not a multiple of 8. > > You can add "-Wa,-adhlns=$(@:.o=.lst)" to kernel_CCASFLAGS > to generate a listing file which shows the offsets of the > labels in the boot_*.S files to verify the alignment issues. > > Note also that the "grub-file --is-x86-multiboot2" utility > does not recognize the wrong alignment of the Multiboot2 > header tags, as it only considers the beginning of the > Multiboot2 header and completely ignores the Multiboot2 > header tags. Please also mention here that you are additionally fixing some formatting errors. Daniel _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org https://lists.gnu.org/mailman/listinfo/grub-devel
