syslinux and isolinux in salix 14.0alpha1

[Adys]

@gapan,

Apparently I am unable to explain this suggestion in a short way, without having to repeat entire wiki pages of the Syslinux project or writing stories of different practical cases.

You are missing the main point of my first suggestion. Other than mentioning specific bootable CDs using the method I am suggesting, I don't want to extend the explanation further. The bottom line is that using "/[boot/][syslinux/]syslinux.cfg" gives better results because it covers more situations than using "/isolinux/isolinux.cfg".

Something similar happens with the second one. Clearly I am failing in my explanations. Oh, well...

[gapan]

You are missing the main point of my first suggestion. Other than mentioning specific bootable CDs using the method I am suggesting, I don't want to extend the explanation further. The bottom line is that using "/[boot/][syslinux/]syslinux.cfg" gives better results because it covers more situations than using "/isolinux/isolinux.cfg".

Which situations are these? It already works from CD and it already works from USB.

[Adys]

As I already said, "isolinux" covers CD only, so evidently the CD should work. Then "syslinux" is a generic" term (for the current Syslinux version), so it should work for all cases, isolinux.bin or ldlinux.sys.

When you say it works for USB drives, that's because you are using the isohybrid MBR. Let's see some different situations.

1._ I copy the content of the ISO image or the CD to my (already bootable) UFD (no erasing my UFD with the dd command; no new partitions generated by the dd command). I then run

Code: Select all

syslinux -i /syslinux/ /dev/sdb1

where sdb is my UFD. This uses ldlinux.sys, which searches for "/syslinux/syslinux.cfg". According to the official documentation, it won't be searching for "/isolinux/isolinux.cfg".

2._ The USB media has no MBR because the BIOS where I want to use it has problems with such devices. The UFD is already working correctly and identified as a (super)floppy in the BIOS. Thus, I don't want to dd the media nor use any MBR on it. I can use a similar method as in the case #1 above.

I could provide more examples where the user doesn't want (or can't) use the isohybrid MBR. Thus, using "/syslinux/syslinux.cfg" instead of the current "/isolinux/isolinux.cfg" covers more potential cases and simplifies the procedure.

If you need different reactions or procedures according to the specific loader (isolinux.bin or ldlinux.sys), then using "isolinux.cfg" is one valid alternative to differentiate the cases (the different media). I don't think this is the case with Salix images.

About the second suggestion, maybe I should upload a small ISO image as a practical example

[JRD]

About using a common syslinux.cfg, why not if we're using syslinux4. But we must be sure that this file do not contain some reference to a CD or something like this. I also think it is clearer to use one common config file for all variant of syslinux. But for you information, it works with some previous version of syslinux, not starting from 4.0.

About the COM module for checking md5sum, it could be a good idea. Especially for the LiveCD. For a regular installation like gapan managed to release, I don't think it's as usefull because all is run from the initrd. But it could no harm to add this option in my opinion.

I'm currently looking for how the Arch ISO is done. I may pick some good ideas they had

[Adys]

it works with some previous version of syslinux, not starting from 4.0.

Officially, "syslinux" is a generic term since v.4.02. And the 2 examples I wrote before show the advantage over the "isolinux" path (which works for CD or for isohybrid MBR on UFD, but not for other UFD methods).

About the COM module for checking md5sum, it could be a good idea. Especially for the LiveCD. For a regular installation like gapan managed to release, I don't think it's as usefull because all is run from the initrd. But it could no harm to add this option in my opinion.

I'm currently looking for how the Arch ISO is done. I may pick some good ideas they had

Since the standard installation CD and the Live CD both boot with the ISOLINUX boot loader, adding the md5sum.c32 module and one md5 file is simple and very easy for the user, so it is useful for both types of CDs. The most important advantage is the instructions for the final user.

When a user comes here and says "I can't boot" or "it hangs", usually the first request is to confirm that the official md5 of the ISO image matches the one from the downloaded file. Then there is the check of the optical media, and the instructions may differ from distro to distro, or from standard CD to Live CD. By using md5sum.c32, the instructions are always the same and no initrd, no anything else other than a successful isolinux.bin, md5sum.c32 and one md5 text file.

Now, sometimes a user says "it freezes while booting, after entering the options in the "boot:" prompt". With md5sum.c32 the check is even simpler, with less steps (less instructions), and less time wasted (no need to load initrd, no kernel, no mounting, no "exit installation").

Of course it doesn't have to be about optical media, since the method works on USB drives too.

I'll try to prepare and upload (somewhere) a very simple ISO image (or two) so to demonstrate the method.

[JRD]

Of course it doesn't have to be about optical media, since the method works on USB drives too.

No need, I already have one. I downloaded an ISO of ArchLinux which do exactly that.

[Adys]

No need, I already have one. I downloaded an ISO of ArchLinux which do exactly that.

Do you mean that you already have an example of md5sum.c32 usage from ArchLinux? Or you are referring to the use of "syslinux" instead "isolinux" paths?

Anyway, I already invested the time to build a simple 410KiB ISO image using both suggestions. I would had already attached it here, but the option is not allowed. If you are still interested, just let me know and I'll try to upload it somewhere.

[JRD]

Well in fact ArchLinux do it in the initrd...so yes, I'm interrested in your example. Feel free to mail it to me : jrd@enialis.net thx.

[Adys]

Well, 14.0 beta1 is now out .

FWIW, I still think that using "/boot/syslinux/syslinux.cfg" (including the "/boot/" directory and "sys" instead of "iso") for all new Salix images (standard install, live, x32/x64, Xfce/MATE/..., ISO/TAR, ...) reduces potential installation problems. Unfortunately Beta1 is still using "/isolinux/isolinux.cfg".

@JRD, you might still have the info I sent you. If interested, don't hesitate to ask.

[gapan]

It's too late to change this now. Since it didn't get into the beta release, such a critical change is not going to make it in the RCs or final releases. It already works, so I'm not going to fix it.

But feel free to fork the iso-creation scripts in github, make any changes you think are best and then do a pull request. I'll consider them for a future release (after 14.0).