[gPXE] How to modify the code can not get DHCP information on the2nd

Shao Miller Shao.Miller at yrdsb.edu.on.ca
Fri Nov 5 14:21:57 EDT 2010


sqwbwh wrote:
> At 2010-11-06 01:27:57,"ShaoMiller"<Shao.Miller at yrdsb.edu.on.ca> wrote:
>
>     sqwbwh wrote:
>>     At 2010-11-05 23:42:16,"ShaoMiller"<Shao.Miller at yrdsb.edu.on.ca>
>>     wrote:
>>
>>         sqwbwh wrote:
>>>         At 2010-11-05 23:13:19,"ShaoMiller"
>>>         <Shao.Miller at yrdsb.edu.on.ca> wrote:
>>>
>>>             sqwbwh wrote:
>>>>             At 2010-11-05 22:39:05,"ShaoMiller"
>>>>             <Shao.Miller at yrdsb.edu.on.ca> wrote:
>>>>
>>>>>>>>                 sqwbwh wrote:
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>                 How to modify the code can not get DHCP
>>>>>>>>>                 information on the 2nd?(GPXE only used to boot
>>>>>>>>>                 the system from ISCSI)
>>>>>>>>>                 Is to remove this step.
>>>>>>>>>                 net0: 00:0 c:: 29:08:11:35 on UNDI-PCI02: 01.0
>>>>>>>>>                 (OPEN)
>>>>>>>>>                 [Link: up, TX: 0 TXE: 0 TX: 0 rxe: 0]
>>>>>>>>>                 DHCP (net0 00:0 c: 29:08:11: d5 ).... ok
>>>>>>>>>                 net0: 192.168.0.202/255.255.255.0
>>>>>>>>>
>>>>>>>>>
>>>>>>>>>                 This can speed up boot speed.
>>>>>>>>>                 Normal GPXE run to start from the boot system
>>>>>>>>>                 tftp process takes about 8 seconds or so
>>>>>>>>>                 If removed from the second time for DHCP
>>>>>>>>>                 information will only need a very quick 2.5
>>>>>>>>>                 seconds.
>>>>>>>>>
>>>>>>>                 Miller, Shao wrote:
>>>>>>>>                 You most likely want the 'use-cached' option.  It is DHCP gPXE encapsulated option number 178.  Or, you can set it in an embedded script:
>>>>>>>>
>>>>>>>>                   #!gpxe
>>>>>>>>                   set use-cached 1
>>>>>>>>                   autoboot
>>>>>>>                 Gene Cumm wrote:
>>>>>>>>
>>>>>>>>                 What file and version are you using? It sounds
>>>>>>>>                 as if you're using
>>>>>>>>                 undionly.kpxe or a .pxe file. undionly.kkpxe
>>>>>>>>                 will skip this second
>>>>>>>>                 DHCP request but certain hardware/firmware has
>>>>>>>>                 issues with this,
>>>>>>>>                 assuming you trust the stability of your OEM's
>>>>>>>>                 PXE/UNDI stack.
>>>>>>>>
>>>>>>                 sqwbwh wrote:
>>>>>>>                 Shao Miller
>>>>>>>
>>>>>>>                 The method is successful.
>>>>>>>                 Thank you
>>>>>>                 sqwbwh wrote:
>>>>>>>                 yes
>>>>>>>                 thankyou Shao Miller
>>>>>>>                 Your method is useful :)
>>>>>                 Miller, Shao wrote:
>>>>>>                 You’re quite welcome, and thanks for including
>>>>>>                 the list on your other reply. :) Have a nice day.
>>>>>>                 - Shao
>>>>>
>>>>                 sqwbwh wrote:
>>>>>                 Shao Miller
>>>>>                 1:
>>>>>                 i use :
>>>>>                 " set it in an embedded script:
>>>>>>
>>>>>>                 #!gpxe
>>>>>>                 set use-cached 1
>>>>>>                 autoboot
>>>>>                 it's good
>>>>>                 2:
>>>>>                 "It is DHCP gPXE encapsulated option number 178"
>>>>>                 Specifically to ask how to use this method?
>>>>>                 What can explain it in detail?
>>>>>                 thank~you
>>>>                 I enjoy using the search feature at the gPXE
>>>>                 (Etherboot) wiki. Please see:
>>>>
>>>>                 http://etherboot.org/wiki/doku.php?do=search&id=encapsulated&fulltext=Search
>>>>                 http://etherboot.org/wiki/msdhcp
>>>>                 http://etherboot.org/wiki/dhcpd
>>>>
>>>>             ShaoMiller
>>>>             Use the search function.
>>>>             Use hyperlinks to provide you with three options for
>>>>             the introduction of 178 not found.
>>>>             178 keyword search does not find use-cached search did
>>>>             not find the relevant presentation.
>>>>
>>>>             Hehe. Could you give me the answer it?. English is
>>>>             almost a maze for me
>>>>
>>>
>>>             I'm afraid that I'm not sure how to explain gPXE
>>>             encapsulated options any better than they are explained
>>>             in the wiki. DHCP option 175 should be a string of
>>>             bytes. Within that byte sequence, there are sub-options.
>>>             'use-cached' is sub-option 178. So your DHCP option 175
>>>             could look like:
>>>
>>>             0xB2 0x01 0x01
>>>
>>>             where,
>>>
>>>             0xB2 : DHCP gPXE encapsulated option 178.
>>>             0x01 : The encapsulated option's value occupies 1 byte.
>>>             0x01 : The encapsulated option's value is 1 (true).
>>>
>>>             I do not know which DHCP service you use, so I do not
>>>             know how you can reconfigure your service to give PXE
>>>             clients this 'use-cached' option via DHCP.
>>>
>>>         Shao Miller
>>>         dhcp server is msdhcp
>>>         Use 1781.jpg and 1782.jpg is set. Enable use-cached did not
>>>         succeed
>>>         Picture shows what can it?
>>         Those screen-shots show a DHCP option 178, not a DHCP gPXE
>>         encapsulated option 178.
>>
>>         You need DHCP option 175. _Inside_ option 175, you need to
>>         have gPXE encapsulated option 178. See:
>>
>>         http://etherboot.org/wiki/msdhcp#setting_up_a_gpxe_encapsulated_options_on_windows_dhcp
>>
>>         It shows exactly how to create the DHCP gPXE encapsulated
>>         options. 175 is a _container_. 178 ('use-cached') goes inside
>>         that container. Change to option 175 and you will be fine,
>>         since your bytes are exactly as I explained above: Option
>>         178, 1 byte long, value 1. All gPXE encapsulated options go
>>         inside option 175. 0xB2 means 178.
>>
>>         Please remember to carbon-copy the list using Reply-All.
>>
>>     Shao Miller
>>     i do 3.jpg and 4.jpg
>>     but no success
>>     If the screenshots just fine. Like
>>     http://etherboot.org/wiki/msdhcp #
>>     setting_up_a_gpxe_encapsulated_options_on_windows_dhcp
>>     The hyperlink is the CHAP user and password to understand
>>     178 still do not understand.
>     Your screen-shots look good! Except that you are missing the final
>     terminating 0xFF byte! At the end of all gPXE encapsulated
>     options, there should be a terminating byte.
>
>     0xB2 0x01 0x01 0xFF
>
>     0xFF: No more gPXE encapsulated options.
>
>     Also, what version of gPXE are you using? Please use gPXE >= 1.0.0.
>
>     Thank you again for including the mailing-list.
>
> Shao Miller
> embedded script.jpg is add a script as you say
> #! Gpxe
> set use-cached 1
> autoboot
>
> Show dhcp using cached correctly
>
> 178dhcp.jpg is the DHCP settings added 0xb2 0x01 0x01 0xff
> According to this set the client to display the information is 178.jpg
> Does not correctly display dhcp using cached is not where not set
> correctly?
>
As Gene Cumm mentioned, think about which file you are using. Please see:

http://etherboot.org/wiki/pxechaining

This is the file that you are currently using:

gpxe-1.0.1-undi.pxe

- Shao Miller
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