[syslinux] Garbled menu on ISOLINUX

Gene Cumm gene.cumm at gmail.com
Fri Aug 8 15:32:27 PDT 2014

On Aug 8, 2014 1:57 PM, "Eric Ewanco" <Eric.Ewanco at genband.com> wrote:
> We have a system that is designed with no VGA port, graphics card, or
keyboard, only a serial console.  We're trying to boot a Linux via
ISOLINUX.  The problem is that when ISOLINUX comes up, the screen is
usually garbled.  Not always; sometimes it's intact, sometimes it's
completely blank.  When it is garbled, it is NOT the garbled text of a
wrong baud rate.  Rather, it looks like someone is interleaving cursor
escape sequences into the text; there are lots of [ and [H and semicolons
and digits and so forth.

This almost sounds like dropped symbols.

> We were using 4.04 but I downloaded and built 6.02 just to check to see
if it had been fixed, and it was not.  Curiously, when I misconfigured the
image (I put syslinux.c32 into the wrong directory), the brief message I
got (the copyright banner and the error message to press a key to retry)
worked just fine on several tries.  Once I fixed that it broke again.

It comes precompiled.  Try using it without running make at all. Also try

> This is an example of what I see:
> ISOLINUX2;10H6.022;16HEHDD2;21HCopy
> ISOLINUX 6.02   Copyright (C) 1994-2013 H. Peter Anvin et al
> Fourscore and twenty years ago, our forefathers brought forth
>                                                              on this
continent a new nation -- conceived in liberty and
                                             dedicated to the proposition
that all men are created equal.
>                                                        Now we are engaged
in a great Civil War, testing whether this
                                          nation, or any nation, can long
endure. Wrie agre hmet tona [grea2t;
b3attlef1iHeld( of Cthat war. We) hve come [to2 dedi;c3ate5 a portioHn of1
>           that fi9el9d, 4as a f-inal2 r0e1sting3 la[c2e; for4 th5osHe
whoH her.e ave
          thei[r li2ves ;t4h8at HthaPt naetitoen mirghtl[ive2.; It 5is4
>                                 fHitAting and propnerv that we shouildn
do thi.
     [2;6boot: 0Het2;63Hal3;1Hboot:3;7H
> Here much of the text merely disappears at the end.  (I have no idea why
there are no carriage returns - I even added them in and verified it and it
still omits them.  A Unix-format file I've used in the past works fine in
this regard.) Often it's more corrupted, though, sometimes totally
> Here is what it does when I press ^V at the boot: prompt:
> boot:
> ?25l222;16HEHDDo.t0:Copyrightg(C)11994-2013-H.1PeterSAnvintetralAnvin
UetX al
> boot:
> [16L[INU2X 46.02  E;HD1D CoHpI(C)i1994-2013)H.NPeter2Anvin.et[alte4r;
1A0nHvi6n .e0t2 al
> boot:
> The BIOS works fine.  Once Linux is booted, it works fine.  GRUB works
fine (that's installed at a later stage).  Only ISOLINUX has problems.
> I tried changing the baud rate from 115200 to 9600 to no avail.
> If I boot an ISOLINUX image that works on another piece of hardware on
this piece of hardware, it is also garbled, so I suspect it's related to
the hardware - maybe related to the fact that it is headless.  But nothing
else has this problem but ISOLINUX.  Is there any way I can absolutely turn
VGA totally off (not counting "console 0" which I've already done)?  Maybe
by a code hack?
> I have tried xterm, urxvt, and cygwin terminal emulators.

Tried ANSI versus VT100 or to enable escape sequence interpretation?

> I have no idea where these escape sequences could be coming from.  I've
search and searched and searched everything on the web SYSLINUX related to
no avail.  I've looked at the source code.  Please help!  Thanks.
> Here is the configuration file:
> serial 0 115200
> console 0
> default shell
> implicit 1
> display isolinux.msg
> prompt   1
> timeout  600
> label install
>   kernel linux
>   append initrd=initrd ramdisk_size=512000 ramdisk_blocksize=4096
> quiet preloadlog=/dev/null showopts console=ttyS0,115200n8
> label shell
>   kernel linux
>   append initrd=initrd ramdisk_size=512000 ramdisk_blocksize=4096
> quiet preloadlog=/dev/null noinstall showopts console=ttyS0,115200n8

Config looks good.  Considered "SERIAL 0 115200 0x008" our "NOHALT 1"?


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