Syslinux - Mar 2016 - Changes to get CD to boot on EFI System.

I've been the maintainer of the G4L project since 2004, and have had great 
success using syslinux, but yesterday I ran into a machine that would not 
boot from the CD. The system system was a Lenovo L540 notebook, and it 
seems to use EFI? Disabled the Secure EFI, but it still would not boot. 
Comes up with the syslinux menu and seems to load the kernel, but then it 
just stops. Never shows the message about finding the filesystem and 
loading the ram disk? Installed Fedora 23 on the machine from DVD, and 
that went fine, and it setup an EFI boot from grub. Tried loaded the g4l from 
the grub using the same method as non-EFI machine, but it seems to do the 
same thing. 

Is there a process to convert a non-EFI CD system into a system that 
supports EFI, or does one need to create two different setups. Not sure if this 
is something about this notebook, or if it is required by EFI systems. 

Have newer desktop systems from Lenovo, and they don't have this issue. 

Looked online for EFI info, and never found something that explained how to 
setup an image that would do non-EFI and EFI booting, so thought it would 
just be an process of turning off the EFI to make an image, but that doesn't
seem to work? Is there documentation that explains how to do this, or is it
still
being worked out. 

Thanks.

+----------------------------------------------------------+
  Michael D. Setzer II -  Computer Science Instructor      
  Guam Community College  Computer Center                  
  mailto:mikes at kuentos.guam.net                            
  mailto:msetzerii at gmail.com
  Guam - Where America's Day Begins                        
  G4L Disk Imaging Project maintainer 
  http://sourceforge.net/projects/g4l/
+----------------------------------------------------------+

http://setiathome.berkeley.edu (Original)
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On 22/03/2016 15:48, Michael D. Setzer II via Syslinux
wrote:
> I've been the maintainer of the G4L project since 2004, and have had
great
> success using syslinux, but yesterday I ran into a machine that would not 
> boot from the CD. The system system was a Lenovo L540 notebook, and it 
> seems to use EFI? Disabled the Secure EFI, but it still would not boot. 
> Comes up with the syslinux menu and seems to load the kernel, but then it 
> just stops. Never shows the message about finding the filesystem and 
> loading the ram disk? Installed Fedora 23 on the machine from DVD, and 
> that went fine, and it setup an EFI boot from grub. Tried loaded the g4l
from
> the grub using the same method as non-EFI machine, but it seems to do the 
> same thing. 
> 
> Is there a process to convert a non-EFI CD system into a system that 
> supports EFI, or does one need to create two different setups. Not sure if
this
> is something about this notebook, or if it is required by EFI systems. 
> 
> Have newer desktop systems from Lenovo, and they don't have this issue.
> 
> Looked online for EFI info, and never found something that explained how to
> setup an image that would do non-EFI and EFI booting, so thought it would 
> just be an process of turning off the EFI to make an image, but that
doesn't
> seem to work? Is there documentation that explains how to do this, or is it
still
> being worked out. 
I came across something like that if I understand well:
http://www.syslinux.org/archives/2014-November/022780.html

So using syslinux fot EFI booting off an optical media on which an ISO
image is written was not possible then and is still not possible as far
as I know.

I didn't heard of plans to change that situation, please someone correct
me if I am wrong.

Didier

Hi,

Michael D. Setzer II wrote:
> Fedora 23 on the machine from DVD, and 
> that went fine, and it setup an EFI boot from grub.
That's the current state of the art:
EFI booting out of an ISO filesystem does not work with SYSLINUX.

All bootable ISOs i know use GRUB for EFI booting. Even the
option --uefi of program isohybrid is to be used with a GRUB2 equipped
FAT filesystem image that is already in the ISO as its second El Torito
boot image.
Matthew Garrett developed this ISOLINUX+GRUB2 layout for Fedora. Many
other distros follow his example.
The next popular alternative is the layout of grub-mkrescue which boots
both, BIOS and UEFI, by GRUB2 software.
And then there is SuSE which grafts a second ISO superblock and
directory tree onto an ISO which contains a GRUB2 boot image for EFI.
(Less popular only if we count SuSE as 1 user, not by its many human
 users.)

I proposed to mention this peculiarity in the isohybrid article of the
SYSLINUX wiki, but Ady, the only other person who commented on that
proposal, had objections.


Ady:

I understand that it is sub-optimal to deprecate the project's
EFI software in favor of the competition without even knowing
why exactly SYSLINUX EFI fails to boot out of an ISO 9660 filesystem.
But as we see, the question re-occurs after a few months.

How can we augment
  http://www.syslinux.org/wiki/index.php?title=ISOLINUX
  http://www.syslinux.org/wiki/index.php?title=Isohybrid
so that users do not believe to have missed the trick for UEFI booting
from optical media ?


Have a nice day :)

Thomas

Hi,

On 22/03/2016 16:35, Thomas Schmitt via Syslinux wrote:
> Hi,
> 
> Michael D. Setzer II wrote:
>> Fedora 23 on the machine from DVD, and 
>> that went fine, and it setup an EFI boot from grub.
> 
> That's the current state of the art:
> EFI booting out of an ISO filesystem does not work with SYSLINUX.
> 
> All bootable ISOs i know use GRUB for EFI booting. Even the
> option --uefi of program isohybrid is to be used with a GRUB2 equipped
> FAT filesystem image that is already in the ISO as its second El Torito
> boot image.
> Matthew Garrett developed this ISOLINUX+GRUB2 layout for Fedora. Many
> other distros follow his example.
> The next popular alternative is the layout of grub-mkrescue which boots
> both, BIOS and UEFI, by GRUB2 software.
> And then there is SuSE which grafts a second ISO superblock and
> directory tree onto an ISO which contains a GRUB2 boot image for EFI.
> (Less popular only if we count SuSE as 1 user, not by its many human
>  users.)
There is also goofiboot (fork of gummiboot) and even efi-stub if
there is no need to tweak the kernel parameters before booting.

As a reminder, in the latter case an initrd can be embedded in the
kernel as well as a kernel command line, but I digress.

Didier

> I proposed to mention this peculiarity in the isohybrid article of the
> SYSLINUX wiki, but Ady, the only other person who commented on that
> proposal, had objections.
> 
> 
> Ady:
> 
> I understand that it is sub-optimal to deprecate the project's
> EFI software in favor of the competition without even knowing
> why exactly SYSLINUX EFI fails to boot out of an ISO 9660 filesystem.
> But as we see, the question re-occurs after a few months.
> 
> How can we augment
>   http://www.syslinux.org/wiki/index.php?title=ISOLINUX
>   http://www.syslinux.org/wiki/index.php?title=Isohybrid
> so that users do not believe to have missed the trick for UEFI booting
> from optical media ?
> 
> 
> Have a nice day :)
> 
> Thomas
> 
 
If users want to find the "--uefi" parameter for the isohybrid
command,
it is already there, documented. If someone doesn't succeed in this 
matter, it is not for lack of documentation, but rather because they 
don't even contact this Syslinux Mailing List nor read documentation 
(at all, in some cases); I won't even bother mentioning the (many) 
cases I know of relevant developers in popular Linux distros completely 
"misunderstanding" (to put it gently) the matter in question.

I have tried to explain the issues in several ways, more than once, in 
this Syslinux Mailing List (and not only here). I have actually 
followed up some of the consequences of some of those discussions, and 
I must say, I was deeply disappointed. Even posting a _starting step_ 
(yet, very possibly "not-perfect") FAT image for (future) UEFI booting
optical media has been either disregarded or misunderstood.

BTW, the official ".txt/isolinux.txt" documentation currently included
in the official Syslinux archives is _really_ outdated (and that 
document is not the only one). Additionally, several potential patches 
for "mkdiskimage" and for "isohybrid" have been ignored /
wasted /
missed.

Let users keep asking; maybe such reiterative questions might build-up 
some kind of reference, documentation, or - dare I say it - actual code 
improvements or the addition of needed / wanted features.

Regards,
Ady.
 
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On 22/03/2016 16:35, Thomas Schmitt via Syslinux wrote:
...
> How can we augment
> http://www.syslinux.org/wiki/index.php?title=ISOLINUX
> http://www.syslinux.org/wiki/index.php?title=Isohybrid
> so that users do not believe to have missed the trick for UEFI booting
> from optical media ?
+1.

I have read Ady's answer to this message, but still: why not just state
clearly in the first document:
"It is not possible to make a CD bootable on UEFI with ISOLINUX".

It wouldn't be costly at all and would save a lot of users a lot of time.

Sorry Ady but I think that requesting from users that they read all the
documentation and all the posts on the mailing list since two or three
years to find their way even in simple use cases is just too much.

So why not just clearly state simple things like that?

Best,

Didier

On 03/22/16 07:48, Michael D. Setzer II via Syslinux
wrote:
> 
> Is there a process to convert a non-EFI CD system into a system that 
> supports EFI, or does one need to create two different setups. Not sure if
this
> is something about this notebook, or if it is required by EFI systems. 
> 
> Have newer desktop systems from Lenovo, and they don't have this issue.
> 
Look for a "legacy boot" option; otherwise you need the CD-ROM to have
the EFI version of Syslinux or another bootloader on it (the same CD
generally can support both, although it may trigger bugs in some very
early, generally 32-bit, BIOSes.)

	-hpa

Hi,

H. Peter Anvin wrote:
> Look for a "legacy boot" option; otherwise you need the CD-ROM to
have
> the EFI version of Syslinux or another bootloader on it
The "another bootloader" is clear to me.

But what are the prescriptions for preparing a SYSLINUX EFI System
Partition that boots out of a CD ?
(Those built according to
   http://www.syslinux.org/wiki/index.php?title=Install#UEFI
 are known not to be able to do this.)

Do you know examples (ready ISOs or production software for ISOs)
which use SYSLINUX for EFI together with ISOLINUX and do not
have to contain a full-fledged operating system in the ESP ?


Have a nice day :)

Thomas