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Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions
From: |
pelzflorian (Florian Pelz) |
Subject: |
Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions |
Date: |
Tue, 23 Apr 2019 21:50:30 +0200 |
User-agent: |
NeoMutt/20180716 |
This sounds nice and clean. Thank you!
On Tue, Apr 23, 2019 at 08:14:48PM +0200, Thomas Schmitt wrote:
> A disadvantage is that for best overall properties, this layout should
> have the ISO partition start at 512-byte block 64. This needs a second
> superblock and directory tree. About 17 MiB with Guix 0.16.0.
>
The ISO files are offered on alpha.gnu.org only with xz compression.
I suppose most of the 17 MiB would disappear with compression.
> So programs like /sbin/isosize can tell the image size even when the
> ISO has already been copied to USB stick.
>
Sounds like this could be used to get a checksum or maybe GPG
verification of a USB drive that supposedly contains the iso.
> Somewhat off topic:
>
> The script also has a killer for the MBR signature in the EFI image
> file. It gets activated together with partition table erasure by
> export MKRESCUE_SED_IN_EFI_NO_PT=extra
> It is meant for those users who are curious whether block 0 of an EFI
> partition really must look like an MBR to be accepted by EFI firmware.
>
> It would be interesting to learn about EFIs which fail without MBR
> signature.
>
> The specs say that there may be "compatibility code" in a EFI System
> Partition. They talk of "MBR" and understanding partitions in the EFI
> partition. I understand it as "may be there, but does not have to".
>
> Minimal test outside of Guix ISO production:
>
> - Install GRUB and configure it for EFI for 32 or 64 bit as your firmware
> needs. (Both is combinable, as Debian GRUB packages demonstrate.)
>
> - Create a minimal bootable ISO. It will not offer more than a GRUB
> command prompt after it was successfully booted:
>
> mkdir minimal
> touch minimal/empty-file.txt
>
> export MKRESCUE_SED_MODE=original
> export MKRESCUE_SED_IN_EFI_NO_PT=extra
>
> grub-mkrescue -o output.iso minimal \
> --xorriso=./grub-mkrescue-sed.sh
>
This prints
address@hidden ~ [env]$ grub-mkrescue -o output.iso minimal
--xorriso=./grub-mkrescue-sed.sh
grub-mkrescue: warning: Your xorriso doesn't support `--grub2-boot-info'. Some
features are disabled. Please use xorriso 1.2.9 or later..
and yields no output.iso for me. Note that xorriso actually has
version 1.5.0.
Regards,
Florian
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, (continued)
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/21
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/21
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/21
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/21
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/22
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/23
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/23
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Ludovic Courtès, 2019/04/17
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/17
Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/23
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions,
pelzflorian (Florian Pelz) <=
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/23
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/23
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/24
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/24
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/24
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Danny Milosavljevic, 2019/04/25
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/25
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, pelzflorian (Florian Pelz), 2019/04/25
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Thomas Schmitt, 2019/04/25
- Re: [Bug-xorriso] ISO installer image: GPT versus MBR partitions, Danny Milosavljevic, 2019/04/25