[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [Bug-xorriso] Test Proposal for [bug #46716] Protective MBR partitio

From: Alexander E. Patrakov
Subject: Re: [Bug-xorriso] Test Proposal for [bug #46716] Protective MBR partition is not marked as bootable
Date: Wed, 30 Dec 2015 16:51:24 +0500
User-agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.5.0

[re-adding bug-grub to CC]
29.12.2015 23:39, Alexander E. Patrakov пишет:
29.12.2015 22:51, Thomas Schmitt пишет:

Alexander E. Patrakov wrote:
2B: prints "this is not a bootable disk" message

i wrote:
You see a string from the EFI partition 0xef in your old BIOS ?

Yes! And it shows it despite the fact that there is no bootable

Is this string from the very start of /efi.img ?
In this case the BIOS possibly hopped on the only partition (0xef)
and tried to execute the x86 machine code of its Extended Boot Record.

Yes, this is the string from the boot record of that partition.

(pseudo-)protective partition (program variant 2C with EFI
   partition as MBR partition 2)

Not sure if I understand this variant correctly, a report from
xorriso would
be welcome.

The default "mjg" mode 2B appends the ESP as MBR partition 1.
In this case, no partition table entry for the ISO filesystem
is created.
So we end up with a single MBR partition 0xef (to which we do
not want to apply the boot flag).

MKRESCUE_SED_PARTNO=2 in run 2C appends the ESP as partition 2
and leaves partition table entry 1 available for covering the ISO
Now it depends on --protective-msdos-label whether this partition 1
starts at block 1 (in case the option is present) or at block 0
(in case the option is missing).
If the start is at block 0, then the MBR partition 1 is mountable as
ISO 9660.

OK, I see. I will test the case when it starts at block 0 tomorrow.

It works on DG965SS when booted from USB, and also works in KVM.

address@hidden:~/isos$ xorriso -indev minimal-mjg-p0.iso -report_system_area plain -report_el_torito plain
GNU xorriso 1.4.3 : RockRidge filesystem manipulator, libburnia project.

xorriso : NOTE : Loading ISO image tree from LBA 0
xorriso : UPDATE : 821 nodes read in 1 seconds
xorriso : NOTE : Detected El-Torito boot information which currently is set to be discarded
Drive current: -indev 'minimal-mjg-p0.iso'
Media current: stdio file, overwriteable
Media status : is written , is appendable
Boot record  : El Torito , MBR GPT APM
Media summary: 1 session, 6488 data blocks, 12.7m data, 2296m free
Volume id    : 'ISOIMAGE'
System area options: 0x00004200
System area summary: MBR GPT APM
ISO image size/512 : 25952
Partition offset   : 0
MBR heads per cyl  : 64
MBR secs per head  : 32
MBR partition table:   N Status  Type        Start       Blocks
MBR partition      :   1   0x80  0x83            0        25952
MBR partition      :   2   0x00  0xef        25952         5760
GPT                :   N  Info
GPT disk GUID      :      f8e95c1c1b3e76429c3027fb01725a1d
GPT entry array    :      16  192  separated
GPT lba range      :      64  31714  31763
GPT partition name :   1  490053004f004800790062007200690064003100
GPT partname local :   1  ISOHybrid1
GPT partition GUID :   1  f8e95c1c1b3e76429c3127fb01725a1d
GPT type GUID      :   1  a2a0d0ebe5b9334487c068b6b72699c7
GPT partition flags:   1  0x1000000000000001
GPT start and size :   1  19720  5760
GPT partition path :   1  /efi.img
APM                :   N  Info
APM block size     :      2048
APM gap fillers    :      0
APM partition name :   1  HFSPLUS_Hybrid
APM partition type :   1  Apple_HFS
APM start and size :   1  83  6405
APM partition name :   2  Appended2
APM partition type :   2  Data
APM start and size :   2  6488  1440
El Torito catalog  : 224  1
El Torito cat path : /boot.catalog
El Torito images   :   N  Pltf  B   Emul  Ld_seg  Hdpt  Ldsiz         LBA
El Torito boot img :   1  BIOS  y   none  0x0000  0x00      4        2620
El Torito boot img :   2  UEFI  y   none  0x0000  0x00   5760        4930
El Torito img path :   1  /boot/grub/i386-pc/eltorito.img
El Torito img opts :   1  boot-info-table grub2-boot-info
El Torito img path :   2  /efi.img

So, I can agree with making this (or the variant without efi.img duplication) the default layout for grub-mkrescue, but I would also like to see a wiki page describing the rationale for each element of this layout in one place. E.g.:

 - why is GPT present at all?
- how do we know that it is used by at least one system, despite the absence of the 0xee MBR partition?

Alexander E. Patrakov

reply via email to

[Prev in Thread] Current Thread [Next in Thread]