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Re: RFC: UEFI/PXE and emulating grub-legacy-uefi-hacked behaviour


From: Richard Chan
Subject: Re: RFC: UEFI/PXE and emulating grub-legacy-uefi-hacked behaviour
Date: Fri, 27 Apr 2012 13:41:03 +0800

I found what seems to be an incompatiblity when GRUB/UEFI bootp is
used with PXE active: you cannot reuse the same IP address. I.e. you
cannot DHCP twice - once by UEFI/PXE and the 2nd time by GRUB/bootp
The 2nd attempt will fail.

Eg., UEFI/PXE has received address 172.31.0.202.
If I try to reuse the same IP address (either manually by net_add_addr
or via net_bootp) I get the error message "timeout cannot resolve
hardware address".
If I use a different IP address it works.

Hence it seems that with the native PXE stack active you cannot reuse
the same IP for GRUB IP stack and UEFI/PXE.

Is there a command that allows me to shutdown the PXE stack from the
grub shell? Then I might be able to try net_bootp again.






2012/4/26 Vladimir 'φ-coder/phcoder' Serbinenko <address@hidden>:
> On 25.04.2012 22:20, Richard Chan wrote:
>> Hi Vladimir and list
>>
>> "The information from EFI network is used only if efinet is embed in
>> grub.efi. Otherwise you have to call net_bootp manually"
>>
>> 1. How do you "embed" efinet.mod into the image so that
>> grub_efi_net_config is called?
>> I presume you mean somthing different from preload of module?
> No, just preload
>> ./grub-core/kern/efi/init.c:  if (!*device && grub_efi_net_config)
>>
>> ./grub-core/net/drivers/efi/efinet.c:  grub_efi_net_config =
>> grub_efi_net_config_real;
>>
>> The latter function populates the NIC structure from PXE, but in my case, it 
>> is
>> not being called.
> Network config is started only if root is on network. Otherwise network
> config is considered unnecessary and skipped.
>>
>> 2. For net_bootp, I can see the BOOTP request/reply but GRUB will
>> timeout setting the IP address. It is as if it doesn't see the BOOTP
>> reply.
> Do you have full dumps? It's possible GRUB rejects them for some field
> mismatch (not all bootp servers are good).
>
>
> --
> Regards
> Vladimir 'φ-coder/phcoder' Serbinenko
>
>
>
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