[syslinux] Boot prompt ignored

[Ady]

> Using a boot prompt without a menu makes Syslinux 6.03-6 booting the 
> default label only, ignoring the label that was entered. Auto completion 
> of the defined labels works, though. Can anyone confirm this? 
> 
 
I compiled binaries from the (hopefully, temporarily) "revert-9acbffd" 
branch from GeneC. The building environment is using old dependencies 
(i.e. not recent versions).

With the resulting binaries, the aforementioned strange behavior was 
_not_ replicated -- _please_, do not just take this as valid / true; 
this same test _must_ be performed by others so to corroborate this 
result.

But, using binaries from Fedora, 6.03-6.fc24, the problematic behavior 
_can_ be replicated.

It has also been replicated by at least one additional user of 
ArchLinux, by using binaries from 6.03-6 (which is probably the package 
that was used by the original reporter).

Additionally, at least one Debian Sid user is reporting the same 
unwanted behavior with 6.03+dfsg-12. Although the problem is not seen 
with  6.03+dfsg-11, I would not suggest that Debian should revert back. 
but rather that (additional) patches for gcc5+ compatibility should be 
also applied to Debian's packages.

The abnormal behavior cannot be replicated with official 6.03 pre-built 
binaries downloaded from kernel.org.

I have not bothered to test with 6.04-pre1 (as I would consider its 
binaries a waste of time, after they have failed me already in other 
tests).

I should add that typing-in either labels or any other command, the 
result is the same: only / always the default command (label) is 
executed when pressing ENTER. To be accurate, I have not actually 
tested whether it is really the DEFAULT command, or the first LABEL, 
that is being executed.

So, this seems to be some environmental / building issue -- again, 
please do not take this statement as valid / true unless these tests 
are replicated by others.

Considering that most Linux distributions that are already using some 
package based on Syslinux 6.03 are also using relatively-updated 
versions of its dependencies (e.g. gcc5+, binutils 2.23+ and so on), I 
am wondering whether some of the pending problems related to makefiles 
and/or ld files could be the source of this unwanted behavior.

For instance, "HIDDEN was added to ld in binutils version 2.23", and 
the current Syslinux source code (both, 6.03 and current git master 
head) is not using the necessary code to cope with this "HIDDEN". 
Perhaps it is time to add some kind of conditional code in Syslinux's 
"*.ld" files , depending on the version of binutils, so binaries could 
be functional in both cases (binutils prior and/or post/equal to 
version 2.23).

Of course this is just an example, and it might not be the culprit of 
this problem. Yet, the basic concept might be relevant for whatever 
might be generating this issue.

Another possible issue that might come to mind: building with/without 
"CFLAGS += -fno-PIE" or something of that sort.

These are wild uneducated guesses; so much so that calling it a "guess" 
might already be too much. I hope knowledgeable developers will find a 
solution.

Regards,
Ady.