Syslinux - Dec 2014 - Using of pxelinux configfiles for both BIOS and UEFI boot

> On Mon, Dec 8, 2014 at 10:44 AM, Leenders, Peter
> <Peter.Leenders at computacenter.com> wrote:
> 
> > This look promising, if I could separate the config files for the
different
> > boot architectures Bios and UEFI. I have 2 different boot files in 2
> > different locations, but after startup they both  refer to the
> > tftproot/pxlinux.cfg/default config file. The DHCP Option 209 may
solve this
> > if the ZENworks tftp server support this option with different values
> > depending on the architecture. Unfortuanelly til now I didn?t found
out if
> > there is a support for this option.
> 
> No need. Again, you have choices.
> 
> http://www.syslinux.org/wiki/index.php/PXELINUX#Hardcoded_options
> 
> -- 
> -Gene
> 
> _______________________________________________
> Syslinux mailing list
> Submissions to Syslinux at zytor.com
> Unsubscribe or set options at:
> http://www.zytor.com/mailman/listinfo/syslinux
I could be wrong about this, but... I think that it could still be 
possible to get multiple architectures / firmwares mixed together while 
using c32 modules, without dhcp options, and perhaps even without 
applying pxelinux-options.

If I understood correctly, this tftp server can choose between 2 boot 
files, depending on BIOS/UEFI client, and the problem is choosing a 
different config file.

According to prior pcap reports, syslinux.efi searches for syslinux.cfg 
(too), while (l)pxelinux.0 will be searching for "default". This means
that using something *similar* to:

 pxelinux.cfg/default:
  PATH bios
  CONFIG common-config.cfg ::bios
  # the bios modules should be located in the bios subdir

and
 pxelinux.cfg/syslinux.cfg
  PATH efi64
  CONFIG common-config.cfg ::efi64
  # the efi64 modules should be located in the efi64 subdir

could / perhaps / might / work. It would also depend on how the path 
notation is expressed in "common-config.cfg", considering that the 
CONFIG directive is changing the working directory.

This might very well fail too, but perhaps this idea triggers some 
additional feedback from someone else.

Regards,
Ady.

>I could be wrong about this, but... I think that it could still be possible
to get multiple architectures / firmwares mixed together >while using c32
modules, without dhcp options, and perhaps even without applying
pxelinux-options.
>
>If I understood correctly, this tftp server can choose between 2 boot files,
depending on BIOS/UEFI client, and the problem is >choosing a different
config file.
>
>According to prior pcap reports, syslinux.efi searches for syslinux.cfg
(too), while (l)pxelinux.0 will be searching for "default". >This
means that using something *similar* to:
>
> pxelinux.cfg/default:
>  PATH bios
>  CONFIG common-config.cfg ::bios
>  # the bios modules should be located in the bios subdir
>
>and
> pxelinux.cfg/syslinux.cfg
>  PATH efi64
>  CONFIG common-config.cfg ::efi64
>  # the efi64 modules should be located in the efi64 subdir
>
>could / perhaps / might / work. It would also depend on how the path
notation is expressed in "common-config.cfg", considering that >the
CONFIG directive is changing the working directory.
>
>This might very well fail too, but perhaps this idea triggers some
additional feedback from someone else.
>
>Regards,
>Ady.


Hello Ady,



thank you for your responce. I will check out this (hopefully) on Monday and
give a short feedback to the list.

I didn't notice this difference in the search order - but it can be. As far
as I can see in my wireshark snapshots on the efi boot where is no search for a
syslinux.cfg, but maybe on the bios boot, but I haven't one snapshot of this
within reach.



Peter



[cid:image001.png at 01D01628.D16F0040]


-------------- next part --------------
A non-text attachment was scrubbed...
Name: image001.png
Type: image/png
Size: 64797 bytes
Desc: image001.png
URL:
<http://www.zytor.com/pipermail/syslinux/attachments/20141212/03d3307b/attachment.png>

>>According to prior pcap reports, syslinux.efi searches for syslinux.cfg
(too), while (l)pxelinux.0 will be searching for "default". >This
means that using something *similar* to:
>> pxelinux.cfg/default:
>>  PATH bios
>>  CONFIG common-config.cfg ::bios
>>  # the bios modules should be located in the bios subdir
>>
>>and
>> pxelinux.cfg/syslinux.cfg
>>  PATH efi64
>>  CONFIG common-config.cfg ::efi64
>>  # the efi64 modules should be located in the efi64 subdir
>>
>>could / perhaps / might / work. It would also depend on how the path
notation is expressed in "common-config.cfg", considering that >the
CONFIG directive is changing the working directory.
>>
>>This might very well fail too, but perhaps this idea triggers some
additional feedback from someone else.
>>
>>Regards,
>>Ady.
>
>Hello Ady,
>
>thank you for your response. I will check out this (hopefully) on Monday and
give a short feedback to the list.
>
>I didn't notice this difference in the search order - but it can be. As
far as I can see in my wireshark snapshots on the efi boot where is no search
for a syslinux.cfg, but maybe on the bios boot, but I haven't one snapshot
of this within reach.
>
>Peter
Hello Ady,

I checked this now by sniffing with wireshark but there is no search for
pxelinux.cfg/syslinux.cfg in either bios or efi mode before searching for
pxelinux.cfg/default. (using a renamed syslinux.efi in efi64 mode)

If I remove/rename the bootloader ldlinux.e64 the seachorder for efi is:
	Ldlinux.e64
	/ldlinux.e64
	/boot/isolinux/ldlinux.e64
	/isolinux/ldlinux.e64
	/boot/syslinux/ldlinux.e64
	/syslinux/ldlinux.e64
	/ldlinux.e64

If I remove/rename the configfile pxelinux.cfg/default the searchorder for efi
is:

	pxelinux.cfg/uuid (or something similar)
	pxelinux.cfg/macaddress
	...
	pxelinux.cfg/(parts of macaddress)
	...
	pxelinux.cfg/default

and then the  boot fails with a "configuration file not found" error.

Peter