--- docs/grub.texi | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/docs/grub.texi b/docs/grub.texi index 1ce9993a5..f071487d6 100644 --- a/docs/grub.texi +++ b/docs/grub.texi @@ -6433,6 +6433,21 @@ validate the contents of the bootloader embedding area, or in more modern systems with GPT-style partition tables (@pxref{BIOS installation}) where GRUB does not reside in any unpartitioned space outside of the MBR. Disable the Reed-Solomon codes with this option. + +@item --emu-512b +By default on x86 BIOS systems, @command{grub-install} assumes a 512 +bytes sector size when generating and writing the core image. This +option makes grub use the disk's native sector size for addressing the +core image's blocks and a 512 bytes read block size, as often found +with old/buggy system firmware. To that effect, the core image is +spread out so that each read block starts on a proper hardware sector. +Additionally, it enables read block and sector size autodetection in +the @samp{biosdisk} access module by setting the +@samp{biosdisk_autodetect_sector_size} variable to @samp{1}. You should +@emph{only} use this option if you @emph{know} that your system +firmware is buggy and can't handle disks with sector sizes bigger than +512 bytes correctly and your machine is trying to boot off such a disk. +It @emph{will} otherwise break normal operation. @end table @node Invoking grub-mkconfig -- 2.25.1
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