Very slow kernel/initrd download (RPI + U-boot)

[ljfranklin]

(2019-09-05 00:35)NiKiZe Wrote:  make sure that you build an image that includes the nic driver instead of relying on nii/snp interface.

Sorry for the delay. I tried building with `bin-arm32-efi/smsc95xx--lan78xx--snp.efi` which I thought included the two possible Raspberry Pi NIC drivers. But this showed the same slow download behavior as `snp.efi`. Building without `snp` (`smsc95xx--lan78xx.efi`) fails to find any network devices. Looks like Michael added a shortcut build rule for Raspberry Pis to the Makefile here, not sure how he was able to get it working.

(2019-09-05 00:35)NiKiZe Wrote:  But other than that, a tcpdump is probably in order to see where the issue is, if it is re-transmits or similar.

Good call, tcpdump file is here. I started the capture once iPXE booted and killed it after ~10 seconds. The kernel download had only reached ~2% during that time. After ~5 seconds the capture shows a large block of retransmits. The network is healthy and the Raspberry Pi when running u-boot is able to download files using TFTP at expected speeds. Any suggestions for debugging this further?

Thanks for the help!