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FAQ - Frequently Asked Questions
2018-01-23, 08:23 (This post was last modified: 2019-02-15 08:27 by NiKiZe.)
Post: #2
RE: FAQ - Frequently Asked Questions

Ctrl-B is not working in EFI on some machines (but work on others)

Try using ESC, B instead of Ctrl-B.

This also affects other Ctrl shortcuts in the config menu.

Some EFI Firmware creators handle keyboard events differently from what iPXE was developed against and tested on.
The ESC key handling was added as a workaround in
Before was known - and it has not been a priority to fix or test, since it also has the risk of breaking something else.

"Kernel panic - not syncing: VFS" when booting Linux in EFI mode

For the kernel to know which initrd it should load, it needs to be specified on the cmdline mentioned in efi stub documentation

kernel vmlinuz initrd=initram.igz
initrd initram.igz

My USB NIC is not found by iPXE

The ipxe target (for example ipxe.efi), does not include drivers for USB devices. (due to it disabling all other connected USB devices)
A good start for USB is to build ncm--ecm--axge ( you can see buildtargets documentation for how combining drivers work )

I'm using memdisk or sanboot to boot an ISO and bootup fails

In pcbios mode there is INT 13 which is used for disk access, this works fine before any kernel has started.
As soon as the kernel starts up, the real-mode INT 13 interface provided by iPXE's "sanboot" or memdisk ceases to exist.

So first part of boot when kernel and initrd is loaded into memory works fine since that is using above mentioned INT 13. But when the kernel has started there no longer is any way to find that data.
You need to find a different method to provide the system with that data, most Linux distros support some kind of kernel cmdline option to be able to fetch squashfs image over NFS, FTP or HTTP (some have buggy DNS resolution)

When using memdisk there is also the option of searching for and creating a device for the data, but it requires modification of the ISO, and in that case I would recommend to modify it to allow the squashfs to be loaded as an extra initrd instead, See this patch for SystemRescueCd

I'm trying to boot an .efi in bios mode, I'm trying to boot bios code in EFI mode

There sometimes is questions how to run EFI code from bios mode, or bios code from EFI mode.
Since this is different types of environments (think trying to run a mac application on windows) this never* works.

EFI enabled machines have something called CSM (Compatibility Support Module) which when enabled allows for EFI firmware to enter bios mode.
This does generally not allow for EFI code to run bios code.
(* There have been reports of bios code being executed from EFI PXE boot - this is likely a bug/security flaw in that firmware)

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RE: FAQ - Frequently Asked Questions - NiKiZe - 2018-01-23 08:23

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