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

[Ady]

> On Monday, April 4, 2016, 22:01:32, Thomas Schmitt via Syslinux wrote:
> 
> > Jernej Simončič wrote:
> >> As long as you have cygwin with development tools installed, it's just
> >> ./configure && make.
 
 
I am not opening a discussion here, but I feel compelled to warn some 
causal reader(s)... Again, that's not really "easy, for everyone". It 
might _sound_ easy, but, for some reason, people with (computer's) 
technical skills tend to forget that most users don't have them.
 
 
> > autotools magic. I myself have few clue of contemporary MS-Windows.
> 
> Well, cygwin is just barely Windows :)
> 
> >> https://eternallybored.org/misc/xorriso/xorriso-1.4.2-cygwin32.zip
> 
> > Options -b and -e want the image file path in the ISO, not on hard disk.
> > I assume that "CD\isolinux\boot.bin" will show up as "/isolinux/boot.bin".
> > Please adjust to "/cd/isolinux/boot.bin" if i am wrong.
> 
> I'll use isolinux.bin directly - oscdimg complained that it's too
> large, so I just dded the first 2048 bytes to boot.bin to get it to
> shut up.
> 
 
 
Of course, that will certainly make the BIOS boot fail (as it did). 
Whether it influences the resulting UEFI part when using oscdimg, I do 
not know.
 
 
> > Option -a might be similar to xorriso command -find ... -exec report_lba.
> 
> -a is just because I'm curious - doesn't make a difference.
> 
> > Option -m is a bit obscure to me. ISO 9660 max size is 2 exp 43 = 8 TiB.
> 
> This one isn't actually necessary with my test, since the resulting
> ISO is small enough, but IIRC, without it oscdimg won't make ISOs
> larger than 700MB.
> 
> > Option -o looks like an interesting feature.
> 
> It's very useful when you have duplicate files.
> 
 
 
When testing / troubleshooting, KISS. We should try to avoid using 
parameters that are not essential for the relevant tests.
 
 
> > I wonder how oscdimg.exe knows that it has to apply boot-info-table
> > patching to the boot.bin file.
> 
> Probably doesn't - the resulting ISO doesn't boot in BIOS mode in
> VMWare (isolinux reports Image checksum error). In EFI mode both
> xorriso and osdcimg-produced ISO fail the same way - "Virtual machine
> encountered unhandled exception in firmware".
> 
 
At any rate, Peter has confirmed what has been my guess all along. That 
also suggests the reason why there has been no public comments from 
Syslinux developers in any of our prior (and long) discussions about 
isohybrid, ISOLINUX or mkdiskimage, whether regarding BIOS or UEFI (and 
so, no proposed-patch implemented :( either).

Regards,
Ady.