[syslinux] Changes to get CD to boot on EFI System.

[Ady]

> 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 
 
 
ISOLINUX is not for UEFI, just as it is not for cooking, and it is not 
for investing in Wall Street.

Unfortunately, this is going to sound as "being negative" to some 
readers. I don't want to, and I don't like it, but I'd rather not give 
a false impression.

There are no magic bullets. People have to invest their own time to 
understand how things work. I have said this before: I have not found 
_just one_ article / blog / post / document explaining everything about 
UEFI in plain clear words without mixing terminology from "basic UEFI" 
(i.e. what is originated from the 1600+ UEFI specs pages alone) with 
some particular UEFI bootloader, or with some particular case, or with 
some other assumption.

For me to be able to understand and differentiate "basic UEFI" from 
additional assumptions, I have had to read different documents, 
comparing between them, re-read, then re-read, then search a little 
more, then re-read...

IMHO, there is no _simple_ way to "explain UEFI" in a _practical and 
effective_ manner, especially with so many "documents" with inaccurate 
/ mixing information.

Regarding the Syslinux wiki, I am still against adding "information" 
explaining what some subject "is not". A minor, aside note might be 
accepted in some cases, but this is not the case for UEFI matters. 
Whatever we might add explaining "what this tool cannot do", it will 
never be "enough" for someone.

There is an additional reasoning. As long as users keep contacting The 
Syslinux Project with questions and requests, such feedback can 
potentially trigger new developments (and improvements / corrections). 
If users read "Syslinux cannot..." in (semi-)official documentation, 
such expressions usually turn very fast in FUD, and in users not even 
bothering to check whether things are really "as bad as they seem"; 
they just move on. It has happened before (and it is still happening). 
It will not matter if in the future the support is extended, the damage 
with inaccurate information will be "done".

Regarding things that are BIOS-only (e.g. ISOLINUX), some improvements 
in the Syslinux code have been made. For instance, v.6.04-pre1 is 
supposed to build the c32 modules that are BIOS-only under the BIOS 
subdirectory only, without the "corresponding" (fake) c32 modules in 
the efi{32,64} subdirs. As a common user, I have higher expectations, 
such as relevant, working c32 modules for UEFI, but at least we now 
have a first-step improvement. I still hope for further developments.

Regarding the ISOLINUX and the Isohybrid wiki pages in particular, I am 
still against trying to explain "too-much" in these particular pages. 
As common user, I have been learning, about bootloaders in general and 
ISOLINUX in particular, not by reading just one document, but by 
practice and iteration (and reading, a lot). By investigating how ISO 
images are built by others (typically, by Linux distros), I have 
learned (during time, with practice, reading, testing, repetitively) 
more than I could have ever learned by reading the Syslinux 
documentation alone.

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. (Yes, I 
am intentionally repeating here this paragraph I already wrote in a 
prior email.)

IMO, expanding the ISOLINUX and Isohybrid wiki pages "too-much" would 
not really answer many more practical questions for _common users_. At 
some point, it could give the impression of "too much for me to read / 
care", which would be even worse than the generic information that is 
currently provided.

I have either read or tested many different methods of building ISO 
images and "how to write to USB" in different (Linux) distros. This is 
how I really learned, and this is how I have been able to report bugs 
and request for enhancements too.

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. (Yes, I am intentionally repeating here this paragraph I 
already wrote in a prior email.)

As it is right now, ISOLINUX is for BIOS, not UEFI. IMHO, the feature 
request for booting optical media in UEFI mode should be aimed at 
"syslinux.efi". But, even booting the "ESP" FAT image (forget about 
accessing the whole optical media at this point) has not been achieved 
(and the FAT image I posted some time ago would only be a first step).

Indeed, my opinion is against this kind of "information" in the 
ISOLINUX and/or Isohybrid wiki pages. Just as I am against going into 
the details of each "building ISO images" methods / scripts / tools of 
each (Linux) distribution in the same pages of the Syslinux wiki. Such 
additions are "never-ending" and "never enough", mostly bloating and 
rarely contributing to _effective practical_ consequences. For 
instance, I want readers to find the "--uefi" option, and adding words 
to these pages will make such simple task more difficult. And yet, some 
developers fail to even read / find such minimal detail already.

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.

BTW, probably Didier might recall this, from almost a year ago:
 http://www.syslinux.org/archives/2015-April/023381.html .

Regards,
Ady.
 
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