[travisb-nexthop]

Pre-submission checklist

• I've ran the linters locally and fixed lint errors related to the files I modified in this PR. You can install the linters by running pip install -r requirements-dev.txt && pre-commit install
• pre-commit run

Summary

iPXE commit de4302490 fixed a bug where empty TFTP files were mistakenly accepted through a NULL pointer access mapping to a real page.

After that change, a file of zero size is rejected because block bitmap operations fail when the bitmap does not exist.

Make the pxeboot_complete marker file not empty so it has a real size and is therefore supported.

Test Plan

Prior to this fix, iPXE would fail downloading the marker file and therefore fail the installation:

autoexec.ipxe... ok                                                                                                                                                                                                                                                          
http://[fc00:125::1000]:6969/dc-da-4d-fc-ad-2d/pxeboot.FBOSS-Distro-Image.x86_64-1.0.initrd... ok                                     
http://[fc00:125::1000]:6969/dc-da-4d-fc-ad-2d/pxeboot.FBOSS-Distro-Image.x86_64-1.0.kernel... ok                                     
tftp://[fc00:125::1000]/pxeboot_complete... Result too large (https://ipxe.org/460f2085)                                                                                                                                                                                     
Could not boot: Result too large (https://ipxe.org/460f2085)                                                                          
ERROR: Boot option failed

Afterwards, it successfully proceeds past that point:

autoexec.ipxe... ok                                                                                                                   
http://[fc00:125::1000]:6969/dc-da-4d-fc-ad-2d/pxeboot.FBOSS-Distro-Image.x86_64-1.0.initrd... ok                                     
http://[fc00:125::1000]:6969/dc-da-4d-fc-ad-2d/pxeboot.FBOSS-Distro-Image.x86_64-1.0.kernel... ok                                     
tftp://[fc00:125::1000]/pxeboot_complete... ok                                                                                        
EFI stub: Loaded initrd from LINUX_EFI_INITRD_MEDIA_GUID device path