Could narrow the problem down to both a Grub issue, but more relevant - to a Dell BIOS issue as well. So, 2 bugs!
Regarding GRUB, the disk information is read through the int 13h/service 48h from BIOS[0]. But testing in an HP machine (with HW RAID as well), and comparing that with what we call the EDD kernel module[1] output (the early boot kernel code that runs in realmode and performs the exact same query as GRUB), it seems GRUB is only filling the lower 32 bits of the total_sectors variable. This is indeed a bug, and I've reported that to GRUB community [2]. But notice I've mentioned an HP machine...because the Dell machine has an even worse bug. In the case of Dell, the BIOS reading both from kernel EDD module and GRUB as well is 0xFFFFFFFF - this value is the full 32-bit mask filled, which would correspond to a disk of 2TB. In my case, the HW RAID5 exposes a disk of 8TB! So, regardless if GRUB is only filling the lower 32 bits, the value from Dell BIOS is wrong. I've sought Dell support through some Dell contacts I've found in kernel commits [3]; they promptly responded, forwarding internally my issue report to their firmware team, but since then they are quiet - hope they can clarify us on the reason of this bogus return value from their BIOS. GRUB community is also quiet regarding my bug report in their code. [0] https://en.wikipedia.org/wiki/INT_13H#INT_13h_AH=48h:_Extended_Read_Drive_Parameters"; [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/x86/boot/edd.c [2] https://lists.gnu.org/archive/html/grub-devel/2021-01/msg00052.html [3] https://lists.gnu.org/archive/html/grub-devel/2021-01/msg00050.html -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1918948 Title: Issue in Extended Disk Data retrieval (biosdisk: int 13h/service 48h) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/grub2/+bug/1918948/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
