[lfs-support] Kernel bug involving physical to virtual remapping

Hazel Russman hazeldebian at googlemail.com
Thu Jul 19 05:57:49 PDT 2018

On Thu, 19 Jul 2018 13:54:19 +0200
Frans de Boer <frans at fransdb.nl> wrote:
> >>> However a git bisection showed that this is actually a memory management issue. The kernel commit that caused the problem is :
> >>> [33c2b803edd13487518a2c7d5002d84d7e9c878f] x86/mm: Remove
> >>> phys_to_virt() usage in ioremap().
> >>>
> >>> Reintroducing the code:
> >>> "if (is_ISA_range(phys_addr, last_addr))
> >>> 	return (__force void __iomem *)phys_to_virt(phys_addr);"
> >>> makes the system bootable again. I have also tested this on a 4.15 kernel and it works there too.
> >>>
> Hello Hazel,
> What you inserted is already available as from the 4.13.0 release. But I 
> can't compile 4.13. anymore because I now have gcc 8.1 instead of the 
> former 7 series.
> I continue my search and go for 4.14 where the check is removed. But i 
> guess that will fail too and this is no solution to my problem with 
> systemd freezing just after it found out that it is on a VM.
> --- Frans
> -- 
Yes, I can boot 4.13 kernels without any problems. But I wanted an LTS kernel that can keep up with the newest exploits (especially meltdown) and the next LTS after 4.9 is 4.14. I'm using bare iron, not a VM (and no systemd!), but it's rather old hardware. The processor is an Intel Core Duo. I can send you the cpuinfo if you want it. 

I suspect that if you did build 4.14, it would behave properly; after all, it does for most people. I have 4.15 on my laptop (which has a Via Nano processor) and no problems there. But I'd be happy to carry out any exploratory tests you like on my desktop, since that's the machine that misbehaves.


More information about the lfs-support mailing list