Syslinux - Jun 2015 - boot... round 2

With this config:
$ head -n2 isolinux/isolinux.cfg 
serial 0 9600
default vesamenu.c32

via the "Raw File Port Mode - VirtualBox"

I got this:
$ file /tmp/serial0.txt 
/tmp/serial0.txt: empty


For the kernel log this in turn works OK:
console=ttyS0 console=tty0 ignore_loglevel


Is it really needed, exclusively a physical serial connection for the isolinux
debug?

On 30.06.2015 10:12, poma wrote:
> 
> With this config:
> $ head -n2 isolinux/isolinux.cfg 
> serial 0 9600
> default vesamenu.c32
> 
> via the "Raw File Port Mode - VirtualBox"
> 
> I got this:
> $ file /tmp/serial0.txt 
> /tmp/serial0.txt: empty
> 
> 
> For the kernel log this in turn works OK:
> console=ttyS0 console=tty0 ignore_loglevel
> 
> 
> Is it really needed, exclusively a physical serial connection for the
isolinux debug?
> 
> 
Actually, ISOLINUX's "serial" directive works quite OK for both,
VirtualBox and Virtual Machine Manager(virt-manager).

virt-manager config example:

- Serial Device 1 (Primary Console)
   Device type: file
   Source path: /tmp/serial0.txt

- Serial Device 1 (Primary Console)
   Device type: pty
   Source path: -


$ head -n3 isolinux/isolinux.cfg 

serial 0
default vesamenu.c32

~~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~ ~~~~~~~ ~~~~~~ ~~~~~ ~~~~ ~~~ ~~ ~

But the question remains, what do we achieve with all these "serial"
"thing"?

With a broken ISOLINUX v6, no data flow into serial console.
With those functional - ISOLINUX v4 and v5, in this case, a menu is displayed.

What's the point in:
"A real serial port that can reliably operate at 115200 8n1 may be
necessary."

Gene, is there something special in "A real serial port" usage,
compared to emulated?

~~~~~~~~~~ ~~~~~~~~~ ~~~~~~~~ ~~~~~~~ ~~~~~~ ~~~~~ ~~~~ ~~~ ~~ ~

If someone wants to play with this on Fedora, set it this way:

'live.py' is the 'isolinux.cfg' generator

$ rpm -qf /usr/lib/python2.7/site-packages/imgcreate/live.py
python-imgcreate-23.1-2.fc23.x86_64


$ su
# cd /usr/lib/python2.7/site-packages/imgcreate/

# cp live.py live.py.bkp

Switch to 'isolinux-debug.bin' usage
&
append the "serial 0" directive at the top of the
'isolinux.cfg'

# sed -i 's/isolinux.bin/isolinux-debug.bin/' live.py
# sed -i '/default %/ i\serial 0' live.py


Ref.
http://www.tldp.org/HOWTO/Remote-Serial-Console-HOWTO/configure-boot-loader-syslinux.html

On Tue, Jun 30, 2015 at 4:29 PM, poma <pomidorabelisima at gmail.com>
wrote:
> "A real serial port that can reliably operate at 115200 8n1 may be
> necessary."
>
> Gene, is there something special in "A real serial port" usage,
compared to emulated?
I should restate: A serial port that responds on BIOS IO port 3F8h
that can reliably operate at 115200 8n1 may be necessary.  A USB
serial port that the BIOS doesn't bother setting up for IO port 3F8h
is just random hardware.

In order to utilize it, the serial port should not be utilized for
normal use (mixing gets ugly) and a special build must be made by
changing mk/devel.mk (although it's been a while).  Lines 3 and 4 must
be uncommented and line 5 must be commented out.  Booting such a build
may take a long time while data is pumped over the serial.

Although perhaps not helpful in this case, I'd normally suggest a
simpler config like the following:


#syslinux.cfg-begin
DEFAULT linux
PROMPT 1

LABEL linux
  LINUX vmlinuz
  APPEND initrd=myinitrd.cgz my-options
#syslinux.cfg-end


The sole use such a simpler config could serve in this instance is to
minimize the serial-debug data generated by a working build to compare
against a broken build.

-- 
-Gene