Syslinux - Aug 2014 - testing out 6.03 network booting... (6.03-pre19)

>    
> We are not ready for "prime-time" though.
> Using the "lpxelinux.0" file from 6.03-pre19 ...
> 
> My RHEL5 installs, when  using the "http://" for kernel, initrd
and append lines, seem to be hitting some sort of parameter length limit.
> The culprit seems to be the long "append" line.
> 
> The same append line, when NOT using "http://" work fine. (of
course the initrd and kernel lines don't have http://xxxxxxxxx) and so are
shorter.
> 
> RHEL6 installs works fines with the long parameter lengths, http or
otherwise.
> 
> * I'll try to shorten the WEB url for RHEL5 and see if it goes through.
> 
How long is the parameter length?  Really old kernels had a
511-character limit (current kernels have a 2047-character limit), so it
might not be anything to do with Syslinux...

	-hpa

--------------------------------------------
On Fri, 8/15/14, H. Peter Anvin <hpa at zytor.com> wrote:

 Subject: Re: [syslinux] testing out 6.03 network booting... (6.03-pre19)
 To: "Shantanu Gadgil" <shantanugadgil at yahoo.com>,
"syslinux at zytor.com" <syslinux at zytor.com>
 Date: Friday, August 15, 2014, 5:34 AM
 
 >? ? 
 > We are not ready for
 "prime-time" though.
 > Using
 the "lpxelinux.0" file from 6.03-pre19 ...
 > 
 > My RHEL5 installs,
 when? using the "http://" for kernel, initrd and
 append lines, seem to be hitting some sort of parameter
 length limit.
 > The culprit seems to be
 the long "append" line.
 > 
 > The same append line, when NOT using
 "http://" work fine. (of course the initrd and
 kernel lines don't have http://xxxxxxxxx) and so are shorter.
 > 
 > RHEL6 installs works
 fines with the long parameter lengths, http or otherwise.
 > 
 > * I'll try to
 shorten the WEB url for RHEL5 and see if it goes through.
 > 
 
 How long
 is the parameter length?? Really old kernels had a
 511-character limit (current kernels have a
 2047-character limit), so it
 might not be
 anything to do with Syslinux...

RHEL 5 is kernel 2.6.18.x

Here is my config with the paths/IP overwritten with other characters

--- snip ---
linux  http://aa.bbb.ccc.ddd:80/_PATH_TO_RHEL5_FILES_/vmlinuz
initrd http://aa.bbb.ccc.ddd:80/_PATH_TO_RHEL5_FILES_/initrd.img
append keymap=us lang=en_US noipv6 nomodeset biosdevname=0 selinux=0
ksdevice=eth0 method=http://ee.fff.gg.hhh:80/PATH_TO_MOUNTED_RHEL5_ISO
ks=http://aa.bbb.ccc.ddd:80/_KICKSTARTS/01-aa-bb-cc-dd-ee-ff.ks
--- snip ---
 
What happens is that the install prompt says kickstart file could not be read
(because "-ff.ks" has been chopped off)
Typing it manually and pressing ENTER makes the install go through successfully,
so I don't think its a RHEL5 problem.

Whichever way I count, I could not see 511 chars. :(

The chop off is somewhere around 199-200 characters (if I copy paste the block
in Notepad++)

*** For now, I have removed "selinux=0" from my config file to keep
RHEL5 + HTTP happy.

Regards,
Shantanu

> >? ? 
> > We are not ready for
> "prime-time" though.
> > Using
> the "lpxelinux.0" file from 6.03-pre19 ...
> > 
> > My RHEL5 installs,
> when? using the "http://" for kernel, initrd and
> append lines, seem to be hitting some sort of parameter
> length limit.
> > The culprit seems to be
> the long "append" line.
> > 
> > The same append line, when NOT using
> "http://" work fine. (of course the initrd and
> kernel lines don't have http://xxxxxxxxx) and so are shorter.
> > 
> > RHEL6 installs works
> fines with the long parameter lengths, http or otherwise.
> > 
> > * I'll try to
> shorten the WEB url for RHEL5 and see if it goes through.
> > 
> 
> How long
> is the parameter length?? Really old kernels had a
> 511-character limit (current kernels have a
> 2047-character limit), so it
> might not be
> anything to do with Syslinux...
>
>RHEL 5 is kernel 2.6.18.x
>
>Here is my config with the paths/IP overwritten with other 
>characters
>
>--- snip ---
>linux  http://aa.bbb.ccc.ddd:80/_PATH_TO_RHEL5_FILES_/vmlinuz
>initrd http://aa.bbb.ccc.ddd:80/_PATH_TO_RHEL5_FILES_/initrd.img
>append keymap=us lang=en_US noipv6 nomodeset biosdevname=0 selinux=0 
>ksdevice=eth0 
>method=http://ee.fff.gg.hhh:80/PATH_TO_MOUNTED_RHEL5_ISO 
>ks=http://aa.bbb.ccc.ddd:80/_KICKSTARTS/01-aa-bb-cc-dd-ee-ff.ks
>--- snip ---
> 
>What happens is that the install prompt says kickstart file could 
>not be read (because "-ff.ks" has been chopped off)
>Typing it manually and pressing ENTER makes the install go through 
>successfully, so I don't think its a RHEL5 problem.
>
>Whichever way I count, I could not see 511 chars. :(
>
>The chop off is somewhere around 199-200 characters (if I copy paste 
>the block in Notepad++)
>
>*** For now, I have removed "selinux=0" from my config file to
keep
>RHEL5 + HTTP happy.
>
>Regards,
>Shantanu
 
According to:
 https://www.kernel.org/doc/Documentation/kernel-parameters.txt 

the limit for kernel boot parameters is between 256 and 4096, 
including spaces.

When writing your 'append' line (using 'initrd=...'), you get to
262
characters, plus the kernel line plus one space character in between.

The "-ff.ks" (last characters in your boot command) you mentioned is 
6 characters long. 262-6=256 characters.

But then you report that typing in the exact same full command, it 
boots OK?

Regards,
Ady.

--------------------------------------------
On Mon, 8/18/14, Ady <ady-sf at hotmail.com> wrote:


 But
 then you report that typing in the exact same full command,
 it 
 boots OK?

I don't type the /complete/ command by hand. I let the error box popup
and then I type in the missing 6 characters and then press ENTER.

The installation then continues.
 
Regards,
Shantanu