Re: Regression for PXE boot from patch "Remove the 'bugger off' message" in stable 6.6.18

[Greg KH <gregkh@linuxfoundation.org>]

On Tue, Mar 04, 2025 at 05:59:32PM +0100, Ulrich Gemkow wrote:
> Hallo,
> 
> On Tuesday 04 March 2025, Greg KH wrote:
> > On Tue, Mar 04, 2025 at 03:49:35PM +0100, Ulrich Gemkow wrote:
> > > Hello,
> > > 
> > > starting with stable kernel 6.6.18 we have problems with PXE booting.
> > > A bisect shows that the following patch is guilty:
> > > 
> > >   From 768171d7ebbce005210e1cf8456f043304805c15 Mon Sep 17 00:00:00 2001
> > >   From: Ard Biesheuvel <ardb@kernel.org>
> > >   Date: Tue, 12 Sep 2023 09:00:55 +0000
> > >   Subject: x86/boot: Remove the 'bugger off' message
> > > 
> > >   Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
> > >   Signed-off-by: Ingo Molnar <mingo@kernel.org>
> > >   Acked-by: H. Peter Anvin (Intel) <hpa@zytor.com>
> > >   Link: https://lore.kernel.org/r/20230912090051.4014114-21-ardb@google.com
> > > 
> > > With this patch applied PXE starts, requests the kernel and the initrd.
> > > Without showing anything on the console, the boot process stops.
> > > It seems, that the kernel crashes very early.
> > > 
> > > With stable kernel 6.6.17 PXE boot works without problems.
> > > 
> > > Reverting this single patch (which is part of a larger set of
> > > patches) solved the problem for us, PXE boot is working again.
> > > 
> > > We use the packages syslinux-efi and syslinux-common from Debian 12.
> > > The used boot files are /efi64/syslinux.efi and /ldlinux.e64.
> > > 
> > > Our config-File (for 6.6.80) is attached.
> > > 
> > > Regarding the patch description, we really do not boot with a floppy :-)
> > > 
> > > Any help would be greatly appreciated, I have a bit of a bad feeling
> > > about simply reverting a patch at such a deep level in the kernel.
> > 
> > Does newer kernels than 6.7.y work properly?  What about the latest
> > 6.12.y release?
> > 
> > thanks,
> > 
> > greg k-h
> > 
> 
> Thanks for looking into this!
> 
> The latest 6.12.y kernel has the same problem, it also needs reverting
> the mentioned patch. I did not test Kernels in between but I am happy
> to do so, when this gives a hint.
> 
> Thanks again and best regards

Great, then this is an issue in Linus's tree and should be fixed there
first.

thansk,

greg k-h