[syslinux] Syslinux 5 (i)pxelinux.0 unnecessary PATH requests

[Shao Miller]

On 12/12/2012 07:39, Arends, R.R. wrote:
>>>> On 11-12-2012 at 19:50, in message <50C78092.5030607 at gmail.com>, Shao Miller
> <sha0.miller at gmail.com> wrote:
>> On 12/11/2012 11:37, Arends, R.R. wrote:
>>>
>>> i just build a new ipxelinux.0 with an
>> EMBED=../../syslinux-5/core/pxelinux.0.
>>> i'm trying to load up my vesamenu.c32 menu from http:.
>>>
>>> and offcorse i want this as optimal as possible, with the least needed GET
>> requests.
>>>
>>> OLD situation with v4:
>>> PXE ROM -> ipxelinux.0 (tftp) -> menu.php (http) -> vesamenu.c32 (http)
>>>
>>> NEW situation with v5:
>>> PXE ROM -> ipxelinux.0 (tftp) -> /ldlinux.c32 (http 404) -> //ldlinux.c32 (http
>> 404) -> //boot/isolinux/ldlinux.c32 (http 404) -> //isolinux/ldlinux.c32 etc.
>> etc. -> menu.php (http 200) -> /mods/vesamenu.c32 (http 200)
>>> that can be fixed with adding ldlinux.c32 to the root of my webserver
>> (ugly... but oke).
>>> but then we still have the other libraries, which it tries to fetch in the
>> same directories first, and yes we can add those to the root aswel as a work
>> around.... but i'd love to have them seperate.
>>>
>>> menu.php has the UI directive as /mods/vesamenu.c32 and the PATH as mods
>> configured
>>> but then still with that PATH directive in the menu it still tries to find
>> the libraries in this order:
>>>
>>> GET /libcom32.c32 (http 404)
>>> GET //libcom32.c32 (http 404)
>>> GET /mods//libcom32.c32 (http 200) < --- success!
>>> GET /libutil_com.c32 (http 404)
>>> GET //libutil_com.c32 (http 404)
>>> GET /mods//libutil_com.c32 (http 200) <--- success!
>>>
>>> in my opinion these are atleast 4 unnecessary requests to the webserver
>> before finding the correct one.
>>> and another thing the PATH directive can only be read after ldlinux.c32 is
>> loaded, so ldlinux.c32 should always be in the root?
>>>
>>> i'm looking for a way to configure this to only search the libs and
>> ldlinux.c32 in ./mods/ to limit the needed GETs to the server, speed things
>> up a bit and have a neat directory structure.
>>>
>>> i was already found the 'search_directories' static const in load_env32.c,
>> but after changing that to:
>>>     static const char *search_directories[] = {
>>>       "/mods",
>>>       NULL
>>>     };
>>>
>>> it still does these requests:
>>> GET /libcom32.c32
>>> GET //libcom32.c32
>>
>> Are you using DHCP option 210?  It is documented in doc/pxelinux.txt and
>> is related to where PXELINUX goes looking for things.  Yes, PATH cannot
>> be processed until ldlinux.c32 is fetched, but option 210 is processed
>> before.  - Shao
>
> Shao thanks for you answer, yes option 210 is used and pointing to the root path of the webserver.

I guess that explains why ldlinux.c32 is being searched-for in the root 
path.

> But option 209 is set to menu.php which is actually in the root and not in the subdir '/mods' or '/modules'.
>
> set 209:string menu/?mac=${net0/mac}&subnet=${net0/250:uristring}&asset=${asset:uristring}&serial=${serial:uristring}&product=${product:uristring}&arch=${arch}
> set 210:string https://boot.xxx.nl/
>

That 209 looks familiar. ;)

> Was already thinking of changing 210 to /mods, but then i have to set the 209 different i think to either ../menu.php or the full path (as in set 209:string http://boot.xxx.nl/menu.php)?
>
> Hmm actually i have to change all my paths in the menu too... those are all based on the root. I still wonder if i can hardcode it somewhere in the source to just fetch the needed libraries from a configured directory.
> current content of root dir:
>   check.php
>   installer <-- directory this directory has installers for windows, debian, etc and have their kernel + initrds + other files in subdirs.
>   index.php
>   modules <-- directory where i want to put in memdisk, vesamenu.c32 and all the needed libraries
>   imaging <-- directory
>
> Any ideas, to make it just look in the dir modules without changing option 210?

Use 210 for the initial root path to where at least 5 files will live: 
pxelinux.0, ldlinux.c32, config.c32, libcom32.c32, boot.php.  Have 
boot.php return the following:

   PATH /mods
   DEFAULT newroot
   LABEL newroot
     COM32 config.c32
     APPEND /menu.php?stuff /

where 'stuff' would be generated by boot.php based on what it received 
from your option 209.  Adjust 209 to use boot.php instead of menu.php. 
The final bit of the APPEND line resets the working directory.

- Shao Miller