Re: How to prepare an ISO 9660 CD for booting via GRUB ?

["Vladimir 'φ-coder/phcoder' Serbinenko" <phcoder@gmail.com>]

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Thomas Schmitt wrote:
> Hi,
>
>   
>> I attach the patch I used for dirty checks
>>     
>
> Oh. You already tested.
> And ? Did it boot ?
>
>   
Yes it booted in qemu-tianocore.
>> Why not to determine it [-boot-load-size] from
>> file size by default?
>>     
>
> Because mkisofs doesn't do that, afaik.
> One never knows what happens if one deviates from
> the old ways by default.
>   
Ok, legacy :(. But --efi-boot would have no legacy.
> (See Joliet and grub 1.96. I now go the old
> way by default. So grub-mkrescue 1.96 boots from
> CD.)
>   
It was a grub bug.
>
>   
>> The problem is that I would like to have efi+bios cd with 2 eltorito
>> entries: one with platformid=0 and another one with platformid=0xef.
>>     
>
> Ahum. More than one boot table entry.
> Would they point to different boot images ?
>
>   
Yes
> I.e would we have
>   -b <BIOS-image> [-boot-info-table] --efi-boot <EFI-image>
>
>   
Yes. Prototype is available at
http://bzr.savannah.gnu.org/r/grub/people/phcoder/rescue-efi/ .
> Is it possible to get an exact prescription, what
> info to write at which byte in the boot catalog ?
>
>   
BIOS+EFI one should look like
Validation entry with id = 0
Default entry  (BIOS). I would like that on hybrid BIOS always come in
default entry to avoid hitting BIOS bugs
Section header entry: 0x91, 0xef, 0x0001, 0, ..., 0
Section entry: 0x88, 0x00, 0x0000, 0, 0, <number of sectors in EFI boot
image>, <LBA start>, 0, ..., 0
In case of just EFI the Section header entry and Section entry become
Validation entry and default entry.
> I have a PDF: El Torito 1.0, January 25, 1995.
> Figure 1, "Multiple Boot-Image Configuration"
> seems to be what you intend.
> I will try to match this with the existing code
> in libisofs (by Vreixo Formoso).
>
>
> ------------------------------------------------
>
>   
>>> Do i get it right that you want the LBA [...]
>>> to be as low as possible ?
>>>       
>> Yes and also the offset to files from boot/grub
>> and metadata to reach it
>>     
>
> I learned meanwhile that there is a feature
> "weight" in libisofs by which one can influence
> the sequence of the data LBAs. An IsoNode with
> high weight will get a low LBA.
>
> So this is merely a matter of suitable options
> in xorriso, by which one can put weight on files.
>
>   
Nice
> ------------------------------------------------
>
>
> Have a nice day :)
>
> Thomas
>
>
>
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>
>   


-- 
Regards
Vladimir 'φ-coder/phcoder' Serbinenko



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