linux-kernel - *Wrong EFI loader signature.* logged on non-EFI boot

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Date:   Sun, 21 Feb 2021 22:22:56 +0100
From:   Paul Menzel <pmenzel@...gen.mpg.de>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, Chao Fan <fanc.fnst@...fujitsu.com>
Cc:     linux-kernel@...r.kernel.org
Subject: *Wrong EFI loader signature.* logged on non-EFI boot

Dear Linux folks,

Linux built with the attached config and `ARCH=i386`, and booted over 
GRUB (coreboot payload or UEFI/CSM in MBR) logs the message below. The 
message is visible on the monitor, and on serial only with `earlyprintk`.

```
Wrong EFI loader signature.
early console in extract_kernel
input_data: 0x016d90aa
input_len: 0x007472dc
output: 0x01000000
output_len: 0x00d5dad4
kernel_total_size: 0x00e3d000
needed_size: 0x00e3d000
Physical KASLR using RDTSC...

Decompressing Linux... Parsing ELF... Performing relocations... done.
Booting the kernel.
[    0.000000] Linux version 5.11.0+ (root@...6de04e878) (gcc (Debian 
10.2.1-3) 10.2.1 20201224, GNU ld (GNU Binutils for Debian) 2.35.1) #268 
SMP Mon Feb 15 06:29:12 UTC 2021
[…]
```

It’s unexpected to see the EFI loader signature to be checked in this 
scenario.

Kind regards,

Paul

View attachment "config" of type "text/plain" (114345 bytes)