[syslinux] EFI: ipxe + syslinux = Failed to read blocks: 0xC

[Oscar Roozen]

Hello dear list,

Using VMware I built a test setup of a server with dhcp, tftp and a 
http-server and several pxe-clients with EFI mode turned on. This setup 
worked, albeit with the exponential-like decay of IO rate I described 
earlier. The work-around of using HTTP works beautifully though.

So it was time for the next step. Migrate this setup to our automated 
testing environment that runs under qemu-kvm. For this I had to use OVMF 
so the nodes would boot in EFI mode (or should I say "UEFI mode" ?). 
This setup uses ipxe roms  to boot over the network.

The short story is that I never got further than syslinux proclaiming 
"Failed to read blocks: 0xC" before even getting to the stage where it 
tries to load ldlinux.e64. Searching for answers I found a thread on the 
qemu-devel list discussing this problem. The user mjt (Michael Tokarev, 
also on this list) found a branch of ipxe that contains two patches that 
should solve this problem. See 
http://www.syslinux.org/archives/2015-June/023582.html for more on this. 
Those patches haven't been merged to the master branch on ipxe.org yet.

Unfortunately whichever version of IPXE or syslinux I try, the result is 
always:

    iPXE 1.0.0+ (87981) -- Open Source Network Boot Firmware --
    http://ipxe.org
    Features: DNS HTTP TFTP EFI Menu

    net0: ec:b1:d7:75:e5:24 using NII on NII-PCI02:00.0 (open)
       [Link:down, TX:0 TXE:0 RX:0 RXE:0]
       [Link status: Unknown (http://ipxe.org/1a086194)]
    Configuring (net0 ec:b1:d7:75:e5:24)...... ok
    net0: 10.X.167.253/255.255.0.0 gw 10.X.255.254
    Next server: 10.X.255.254
    Filename: efi64/syslinux-87020-debug.efi
    tftp://10.X.255.254/efi64/syslinux-87020-debug.efi... ok
    efi_rdwr_sectors: read 1 bytes
    Failed to read blocks: 0xC

In this screenshot the iPXE version is 87981 for commit 87981bb6. The 
syslinux version here is 87020-or for commit 8702009f plus one extra 
printf I added, that shows me the error happens on the very first call 
to efi_rdwr_sectors while reading one byte.

This iPXE comes from git://git.kraxel.org/ipxe, but I also tried stock 
version 1.0.0+ and 2b15ae55 and the newest ae7f22eb2  from 
git://git.ipxe.org/ipxe.git. For syslinux I used the precompiled binary 
from syslinux-6.03.tar.gz, the result of 'make spotless; make efi64' on 
that tar. Furthermore I checked out the master branch from 
git://repo.or.cz/syslinux.git which gave me the 8702009f commit. I also 
tried 23b2707b for reasons I forgot.

For OVMF I tried both edk2.git-ovmf-x64-0-20150716.b1120.g387e7c1.noarch 
from https://www.kraxel.org/repos/jenkins/ and a freshly built version 
of commit 2ad9cf37 from https://github.com/tianocore/edk2.git.

But I think I can rule out any influence from either qemu or 
ovmf/tianocore/edk2 or some misconfiguration of libvirt on my behalf, 
because while I was busy troubleshooting this, a shiny new piece of real 
hardware arrived: a HP Proliant DL360 gen9. So I got to play with real 
hardware!

Unfortunately, the error above was actually cut and pasted from the 
ipmi-console session to this HP...

Needless to say I tried all combinations of ipxe + syslinux on this HP 
as well, but no luck whatsoever. Always:

     >> Booting Embedded LOM 1 Port 1 : HP Ethernet 1Gb 4-port 331i
    Adapter - NIC (PXE IPv4)

     >> Booting PXE over IPv4.
       Station IP address is 10.X.167.251

       Server IP address is 10.X.255.254
       NBP filename is efi64/snponly.efi
       NBP filesize is 119488 Bytes
      Downloading NBP file...

       NBP file downloaded successfully.
    iPXE initialising devices...ok



    iPXE 1.0.0+ (87981) -- Open Source Network Boot Firmware --
    http://ipxe.org
    Features: DNS HTTP TFTP EFI Menu

    net0: ec:b1:d7:75:e5:24 using NII on NII-PCI02:00.0 (open)
       [Link:down, TX:0 TXE:0 RX:0 RXE:0]
       [Link status: Unknown (http://ipxe.org/1a086194)]
    Configuring (net0 ec:b1:d7:75:e5:24)...... ok
    net0: 10.X.167.253/255.255.0.0 gw 10.X.255.254
    Next server: 10.X.255.254
    Filename: efi64/syslinux-87020-or.efi
    tftp://10.X.255.254/efi64/syslinux-87020-or.efi... ok
    efi_rdwr_sectors: read 1 bytes
    Failed to read blocks: 0xC

While playing with this HP I found there is a misunderstanding worldwide 
about the contents of dhcp option 93, but this was also discussed 
before: http://www.syslinux.org/archives/2014-October/022684.html. It 
looks like all open source authors correctly use the definition from RFC 
4578 whereas most hardware vendors stick with the definition from the 
DHCPv6 specs which has x64 and EBC the wrong way around. The HP is no 
exception here, but this made it very easy to chainload syslinux after 
ipxe. If dhcpd receives a 0x07, it will respond with ipxe.efi. This will 
then do a request again with the correct (0x09) architecture upon which 
dhcpd responds with syslinux.efi.

My questions:

What can be the cause of error 0x0C which translates to EFI_NO_MEDIA ?

How can I enable debugging on the various components involved?

If some you have iPXE + syslinux working with UEFI somehow, either 
through roms in qemu or by chainloading from snponly.efi, ipxe.efi or 
any other way, please tell me more about your setup?

Can there be some mis-configuration somewhere that can lead to this error?

Or the TL;DR version: HELP! ;-)

In any case, thanks for reading this far into this mail!

Regards,

Oscar Roozen
Linux Developer