[syslinux] syslinux.efi and vendor-class-identifier

James Pearson james-p at moving-picture.com
Tue Oct 8 09:36:25 PDT 2019

James Pearson via Syslinux wrote:
> Gene Cumm wrote:
>> On Fri, Oct 4, 2019 at 7:47 AM James Pearson via Syslinux
>> <syslinux at syslinux.org> wrote:
>>> Ady Ady via Syslinux wrote:
>>>>> We're using a CentOS 6 server running its native (ISC) dhcpd (v4.1.1)
>>>>> and tftpd (v 0.49). I've installed syslinux.efi and ldlinux.e64 
>>>>> from the
>>>>> syslinux-6.04-pre2 distro alongside the existing pxelinux.0
>>>> Please avoid the official binaries from Syslinux 6.04-pre2 and
>>>> 6.04-pre3. Additionally, the current git master head is not useful for
>>>> troubleshooting.
>>>> Whether the specific version actually has any kind of influence on
>>>> these particular tests, I don't know (but, at any rate I would avoid
>>>> the aforementioned versions anyway).
>>>> Please try either official binaries from 6.04-pre1, or from current
>>>> Debian Testing.
>>>> Please avoid mixing Syslinux-related files from different
>>>> versions/builds (within the same platform).
>>> I tried with 6.04-pre1 - it made no difference, the same issue as with
>>> 6.04-pre2
>>> I had a look through the syslinux code, but I couldn't work out if
>>> syslinux.efi is responsible for the 2nd DHCP Discover I see via tcpdump
>>> (I can't pretend to understand the code, so I might not be looking in
>>> the right place)
>>> i.e. is it syslinux.efi that tries a DHCP transaction between
>>> downloading syslinux.efi and downloading ldlinux.e64 - or is this done
>>> by the host's EFI PXE firmware ?
>> Since I don't recall ever seeing this kind of behavior, it makes me
>> think it's system-specific while SYSLINUX initializes the interfaces.
>> I assume you get no output on the screen?
> The hardware I'm using is a Dell 3930 rack mount workstation - but as
> this is the first time I've tried EFI PXE booting, I'm not sure what to
> expect ...
> I get on the screen:
>   Getting cached packet
>   MY IP is
>   core_udp_sendto: stalling on configure with no mapping
>   core_udp_sendto: aborting on no mapping
>   disable UseDefaultAddress
>   core_udp_sendto: udp->Configure() unsuccessful (20)
> I believe the above errors are from the TFTP client in syslinux.efi
> complaining - which is probably because the 2nd DHCP transaction fails ?
> However, I have just tested the exact same boot procedure using a Dell
> laptop (Latitude 7480) - and it all worked without a problem - that is,
> syslinux.efi and ldlinux.e64 were downloaded without a problem - and
> from a tcpdump, there was *no* DHCP transaction between downloading
> syslinux.efi and ldlinux.e64

I've also set up EFI PXE booting of grub - which is just a simple case 
of changing the initial filename to download to "shim.efi" in the DHCP 
config - which then downloads "grubx64.efi" - this works fine on the 
3930 system - and there is no DHCP attempt between downloading 
"shim.efi" and "grubx64.efi" files - I don't really know what this means 
- except, maybe there is 'something' in the way "syslinux.efi" opens the 
connection to download "ldlinux.e64" that is causing the 3930 PXE EFI 
stack to trigger a DHCP Discover request ? (I'm just grabbing at straws 
here ...)


James Pearson

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