[syslinux] EFI Clients Unable to Load kernel/initrd Not Stored on PXE Server

Gene Cumm gene.cumm at gmail.com
Tue Apr 10 07:27:10 PDT 2018

On Fri, Apr 6, 2018 at 3:28 PM, Nathan.Wittie--- via Syslinux
<syslinux at zytor.com> wrote:
> Issue Statement:
> PXE booting from BIOS systems works fine on both 6.03 and 6.04-pre1. New clients only support (u)EFI which results in the inability to load remote kernel or initrd. Tested with both Syslinux 6.03 and 6.04-pre1. So far unable to boot any (u)EFI clients unless both initrd and kernel are on PXE server.
> Using packet captures I see that the URI request for the remote file on the repo mirror looks correct ( ), but the client is asking the PXE server for the files instead of the repo mirror. The PXE server responds with a http 404 packet. User sees "File not found" message on client. Duplicating the directory structure of the Linux Repo Mirror in the HTTP directory of the PXE server results in successful file transfers.
> --Expected Behavior--
> *Menu item set to retrieve files from ""
> *Client looks for files at ""
> *Client gets files from ""
> --Actual Behavior--
> *Menu item set to retrieve files from ""
> *Client looks for files at ""
> *Client gets files from "", if the directory structure has been copied in /var/www/html/

This is certainly an issue however we need to try to separate this
into either a Syslinux issue or a firmware issue.

Did you happen to test HTTP versus TFTP?

> System used for initial testing
> *ESXi 5.5U3 VM Version 8 (EFI mode)
>         NIC - vmxnet3

At one point, I remember having a lot of issues with a VMHW v9 VM when
I was working on a multi-NIC issue and changed to doing most of
testing on VMHW v10 with VMware Workstation 12 or ESXi 6.5 however I
still tend to test with VMHW v8 on BIOS.

> *Dell R7425 (AMD Epyc based), does not offer a "BIOS" mode
>         NIC - Broadcom 57412 (10G SFP+), FW
>         BIOS - 1.1.3
> Example Systems:
> *dhcpd Server -
> *Internal Linux Repo Mirror -
> *Prod BIOS PXE (syslinux-6.03) -
> *Test UEFI PXE (syslinux-6.04-pre1) -
> *ESXi 5.5U3 VM Version 8 (EFI mode) -

Snipping off the instructions for now.

And thank you for so carefully documenting your test procedure.


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