[syslinux] Option to create livecd using new syslinux to support multiple machines.

Matt Fleming matt at console-pimps.org
Fri Jul 5 03:51:29 PDT 2013

On Fri, 05 Jul, at 07:15:32PM, Michael D. Setzer II wrote:
> Wondering what the best process would be to create livecds using 
> the newer version of syslinux.
> Currently my G4L project has just been upgraded to syslinux 5.10 
> and works fine with regular 32 and 64 bit systems using the 32bit 
> kernels, but have seen comments about EFI and somethings 
> about 32bit only working with 32bit and 64bit with 64bit?

I'm super happy to hear about your success with 5.10.

Here is the break down of issues with EFI and 32/64-bits in 6.01...

EFI firmware will only load a bootloader built for the same bitness,
e.g. 32-bit EFI firmware will only load Syslinux efi32 and 64-bit
firmware will only load Syslinux efi64. There's no easy way around this.

Currently, the support for booting a 32-bit kernel from Syslinux efi64
is sitting in a topic branch on my hard disk, and while booting a 64-bit
kernel from Syslinux efi32 may work out of the box now, it hasn't been
tested as far as I know (it's also a lot less useful for most people).

Lots of people have requested the ability to boot a 32-bit kernel from
Syslinux efi64, so merging the topic branch is pretty high up on my TODO
list. I'm thinking I'll get to it some time next week.

One further thing to mention while we're discussing mixing bitness - the
kernel currently has no EFI runtime support when you mix firmware/kernel
bitness. For instance, the following boot scenario,

    64-bit firmware -> Syslinux efi64 -> 32-bit kernel

will mean that once you've booted your kernel, you won't be able to
read/write EFI variables. I do have plans to add support for this in the
> Since I average about 1,000 downloads per week, I would expect 
> that a range of computers are being used, so looking if a single 
> setup will continue to work, or if multiple builds will be required?

I know that Fedora provides livecds that work with BIOS and EFI using
the isohybrid scheme. I'd suggest looking to see what they're doing.

Matt Fleming, Intel Open Source Technology Center

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