[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.

-- 
Hazel


More information about the lfs-support mailing list