Le jeu. 6 juil. 2023 à 16:20, Michael D. Setzer II <[email protected]> a écrit :
> On 6 Jul 2023 at 15:17, lacsaP Patatetom wrote: > > From: lacsaP Patatetom <[email protected]> > Date sent: Thu, 6 Jul 2023 15:17:14 +0200 > Subject: Re: simple message under BIOS/CSM/LEGACY > To: [email protected] > > > Le lun. 21 nov. 2022 à 10:22, Pascal <[email protected]> a écrit : > > > > > hi, > > > > > > I'm coming back on this subject (eg. display a short message inviting > the > > > user to switch the PC to EFI/UEFI) after some field feedback. > > > > > > here is the simple code now used : > > > > > > ; nasm nobioscsm.asm -f bin -o nobioscsm > > > bits 16 > > > org 0x7C00 > > > start: > > > sti > > > cld > > > mov si, msg > > > mov ah, 0x0E > > > .loop lodsb > > > or al, al > > > jz halt > > > int 0x10 > > > jmp .loop > > > halt: > > > hlt > > > jmp halt > > > msg: > > > db 0x0D, 0x0A, 'Boot with BIOS/CSM/LEGACY no longer supported : > reboot > > > with EFI/UEFI', 0 > > > > > > and here is what appears on the screen (Lenovo Thinkcenter M720) > instead > > > of the expected message : > > > > > > [image: clover.jpg] > > > > > > > > > the problem occurs mainly with the Lenovo brand (Thinkcentre M70 > > > <https://www.google.com/search?q=Lenovo+Thinkcenter+M70>, Thinkcentre > M720 > > > <https://www.google.com/search?q=Lenovo+Thinkcenter+M720>), but not > only > > > according to my information. > > > > > > changing the partitioning to BIOS/Intel/MBR (instead of GPT) does not > > > change the problem : this last point makes me strongly believe that the > > > problem comes from the code... > > > > > > regards, lacsaP. > > > > > > Le mer. 3 août 2022 à 23:50, Pascal <[email protected]> a écrit : > > > > > >> thanks for the track of the second active partition (as Ubuntu does > > >> according to exchanges on the syslinux mailing list). > > >> I'll try it, but I'm wondering if I'm not going to abandon GPT > > >> partitioning in favor of DOS partitioning which remains fully > operational > > >> under UEFI... > > >> > > >> Le mer. 3 août 2022 à 20:25, Pascal Hambourg <[email protected]> > a > > >> écrit : > > >> > > >>> Le 03/08/2022 à 16:11, Pascal a écrit : > > >>> > *this is python biting its tail ;-)* > > >>> > > > >>> > here is what I plan to test : > > >>> > leave the protective partition in place (1), mark it as active (2) > and > > >>> > change its first sector to zero (3). > > >>> > > > >>> > 1) its absence seems to be a problem (at least with qemu/ovmf), > > >>> > > >>> The GPT scheme is usually not recognized without a protective > partition. > > >>> > > >>> > 2) gdisk does not activate it by default, > > >>> > > >>> As expected. Setting the boot flag on the protective partition is > > >>> against the EFI specification. > > >>> > > >>> Also, some UEFI firmware refuse to boot in EFI mode if the protective > > >>> partition has the boot flag set. Setting the boot flag on another > (even > > >>> empty) partition entry has given good results with both legacy and > EFI > > >>> boot. > > >>> > > >>> > the only point that seems contentious to me is whether a partition > can > > >>> have > > >>> > its first sector set to zero ? > > >>> > > >>> In the MBR/DOS partition scheme, it should not because the first > sector > > >>> is reserved for the MBR (but in Sun/BSD disklabel, partition 'c' > starts > > >>> at sector 0 and covers the whole drive). But Debian installation > images > > >>> for x86 are set up this way : > > >>> > > >>> Device Boot Start End Sectors Size Id Type > > >>> sdb1 * 0 1320959 1320960 645M 0 Empty > > >>> sdb2 4288 13343 9056 4,4M ef EFI (FAT-12/16/32) > > >>> > > >>> > > >>> > does the BIOS check this kind of thing ? > > >>> > > >>> Not in my experience, but I haven't used the Debian installer with > all > > >>> existing firmware. > > >>> > > >>> > > hi, > > > > a little feedback on this subject we broached last year. > > > > I think I've identified the problem, which is linked to the workstation's > > UEFI, which "jams" when the GPT is "malformed". > > so, the problem has nothing to do with the little piece of code designed > to > > display the warning... > > > > the USB media is initially "burned" with a small disk image in GPT > format : > > the GPT defined in this small disk image is no longer valid for this USB > > media once the disk image has been dropped onto it (for example, the > backup > > copy expected at the end of the USB media is not there or is not the > right > > one). > > > > disk image > > [[GPT#1][P1 NTFS][P2 ESP][GPT#2]] > > USB media > > [[GPT#1][P1 NTFS][P2 ESP][GPT#2] ] > > - or - > > [[GPT#1][P1 NTFS][P2 ESP][GPT#2] [OLD#2]] > > > > the same USB media "initialized" (this initialization, performed in > > initramfs at first boot, consists in repartitioning the USB media to > occupy > > all its space) on a second workstation that does not pose this problem, > > then no longer poses a problem on the first workstation. > > > > USB media initialized > > [[GPT#1][P1 NTFS:::::::::::::][P2 ESP][GPT#2]] > > > > the repartitioning operation "corrects" the GPT and the recalcitrant > > workstation is no longer recalcitrant following this correction. > > > > I hope I've made my explanations clear. > > > > regards, lacsaP. > > > > (ps : I still don't have any recalcitrant workstation available) > > > > Don't know if this would apply to this. > I create a 64M image file that has GPT disk and contains both a > regular grub4dos boot and a grub4dos-efi boot to load files. > Copy the image to a flash using dd and the GPT has the problem > mentioned. > Use this to correct it. > echo -e "Fix" | parted -l ---pretend-input-tty > > Believe that looking at flash with gparted also prompts to fix it, > but the parted -l is much faster. > > Perhaps has nothing to do, but thought worth mentioning. > > > > +------------------------------------------------------------+ > Michael D. Setzer II - Computer Science Instructor (Retired) > mailto:[email protected] > mailto:[email protected] > Guam - Where America's Day Begins > G4L Disk Imaging Project maintainer > http://sourceforge.net/projects/g4l/ > +------------------------------------------------------------+ > > > > thanks for the feedback. would you know of a similar command under Windows that could fix the GPT ? with a native Windows tool if possible (diskpart KO, cmdlet KO, what else...) ? or even with a small third-party console tool ? I use this script (https://github.com/patatetom/PowerShellBurner) to put my disk image on the USB media : I'd just have to add a few commands at the end to update the GPT... regards, lacsaP.
