Booting Linux kernel under UEFI hangs immediately after download

[langlorx]

I've discovered that a simple sleep 1 before the boot line is all it takes for most installers to boot correctly. Remove any sleep statement and it hangs as it did previously just when executing boot. If there is an imgstat or echo, it does print, but still hangs after if there's no sleep.

There's still an odd issue where CentOS fails to find the mount the initrd rootfs and panics when booting on hardware, yet works in a UEFI-enabled virtual machine. However, Ubuntu and Fedora fully load into the installer with the above fix.

Here's the output with imgstat and EFI debug enabled for Fedora:

tftp://10.1.1.1/ipxe/linux/fc24.bios... ok
EFIIMAGE 0xcc054688 could not load: Error 0x7f048183 (http://ipxe.org/7f048183)
http://ftp.10.1.1.1/fedora/isolinux/vmlinuz... ok
http://ftp.10.1.1.1/fedora/isolinux/initrd.img... ok
EFIIMAGE 0xcc054988 could not load: Error 0x7f048183 (http://ipxe.org/7f048183)
vmlinuz : 6277656 bytes [EFI] [SELECTED] "initrd=initramfs"
initramfs : 48206188 bytes
Sleeping...

And here's the script I used to boot it:

#!ipxe
kernel http://ftp.10.1.1.1/fedora/isolinux/vmlinuz initrd=initramfs
initrd --name initramfs http://ftp.10.1.1.1/fedora/isolinux/initrd.img
imgstat
echo Sleeping...
sleep 60
echo Boot
boot