Odd behavior running under Parallels

[Richard]

All,

I'm seeing some general weirdness trying to use iPXE between VMs for testing. I could use some troubleshooting tips, particularly around what's happening under the hood during file download.

What I'm seeing:
With ipxe.iso, the initrd image will start to load, then hang. The point isn't consistent, but ranges from 65k to 150k into the file.
With pxelinux.0, the full 370MB image will load and boot, but fail for other reasons.
With undionly.kpxe, the process never gets as far as starting the initrd step - it hangs while loading

What I'm wondering:
When the initrd command runs, does it download the whole file first, or does part of the downloaded image start executing partway through the download process? i.e., do I have a simple issue here with a download failing, or is it possible that code inside the image is causing the failure?


I'm running CentOS6.4 on MacOS 10.8.3 using Parallels 8.0.18494, and trying to replicate this boot scheme as a start:
http://blog.braastad.org/?p=332
The goal is to iPXE and run these commands:
dhcp
initrd http://example.com/initrd0.img
kernel http://example.com/vmlinuz0 initrd=/initrd0.img root=/centos64-pxe.iso rootfstype=auto rw liveimg toram size=4096
boot

What I've tried:
Booting from the ipxe.iso demo file, Ctrl-B, and manually entering the commands, trying both HTTP and TFTP as sources
Booting an ipxe.iso file from rom-o-matic with the above script embedded
Chain loading the above in undionly.kpxe form
Booting the image via pxelinux.0
Running tcpdump during the above, and analyzing with Wireshark


I'm suspecting some issue here between iPXE and the Parallels virtual NIC. Among the symptoms, when loading fails (e.g., TFTP timeout) the NIC goes dead - subsequent tries show no packets in tcpdump, and ifopen or dhcp won't work until the interface is ifclose'd first.

I've hit a wall trying to debug this. Any pointers would be appreciated.

Thanks,
Richard