I found out that gPXE has a 4KB TCP_WINDOW_SIZE by default. I got speed problems downloading files with gPXE in HTTP (10 times slower then on the same machine with linux+wget), so I am changing the value of TCP_MAX_WINDOW_SIZE to see if it changes something. Describe the bug in details, be able to reproduce the bug with Qemu for example. I cannot reproduce it with Qemu, it goes at full speed inside Qemu (downloading Tinycore 8MB file in 3 seconds). Bug reported on the gPXE bug tracker.


File gpxe-1.0.0-gpxe.iso. Got it from the web interface of Rom-o-matic (select ISO file and NIC-type: all drivers).


Describe here on how to boot gPXE under qemu with binaries attached.

Boot Openwrt from

Download the following netbootme.iso, and then boot it with Qemu. Then try to get the Gpxe console, and type:


The kernel fails to find the right rootfs…