[syslinux] Automatic boot menu?

[H. Peter Anvin]

On 08/29/2013 04:14 AM, Ferenc Wagner wrote:
> "H. Peter Anvin" <hpa at zytor.com> writes:
> 
>> On 08/22/2013 10:20 AM, Ferenc Wagner wrote:
>>
>>> Now that Syslinux has ls.c32 and lua.c32, it should be possible to build
>>> a customizable boot menu in the bootloader itself, instead of generating
>>> it beforehand by hooking into the kernel installation/removal process.
>>> Sure that would not work over TFTP (no ls), but the already mentioned
>>> 20th century way would not either.  Sadly, directory handling is not
>>> implemented in the embedded Lua interpreter, or at least I failed to
>>> find it.  Is there perhaps some deep reason for this?  Or is this idea
>>> useless anyway?
>>>
>>
>> No, there isn't any reason for that.  It's just a matter of noone having
>> done it yet.
>>
>> It would be a very good thing to get this done.
> 
> Thanks, glad to hear it.  And would it be necessary to reimplement the
> menu system in Lua, or would it be possible to hand over the generated
> config to menu.c32 somehow?  If not, then maybe extending menu.c32 with
> some "dynamic" directives would be a lot easier.  Unfortunately that
> would restrict the functionality to the simple menu system and also make
> it more rigid, but that's probably the bulk of the use cases anyway...
> 

One of the main reasons for the code restructuring into ELF libraries is
that we should be able to set up configurations in memory.  There are
two ways we could do that... either by manipulating the menu data
structures and just making them persistent, or by introducing a concept
of "in-memory files" which persist across modules.

Which one would you think would be easier?  The downside of the latter
is that the existing menu structure would not be available, but the
upside is that we wouldn't be introducing a whole new interface...

	-hpa