[Arm-dev] Community kernel 4.18.x

[Mark Verlinde]

-----Oorspronkelijk bericht-----
> Afzender:Mark Verlinde <mark at havak.nl>
> Verstuurd: Woensdag 17 Oktober 2018 18:49
> Aan: Conversations around CentOS on ARM hardware <arm-dev at centos.org>
> Onderwerp: Re: [Arm-dev] Community kernel 4.18.x
> 
> 
> -----Oorspronkelijk bericht-----
> > Afzender:Pablo Sebastián Greco <pablo at fliagreco.com.ar>
> > Verstuurd: Woensdag 17 Oktober 2018 18:09
> > Aan: Conversations around CentOS on ARM hardware <arm-dev at centos.org>
> > Onderwerp: Re: [Arm-dev] Community kernel 4.18.x
> > 
> > 
> > 
> > El 17/10/18 a las 11:47, Mark Verlinde escribió:
> > > Hi,
> > >
> > > Kernel 4.18.x brings nice features, CPUFreq for Allwinner H3 SOC's being among them.
> > >
> > > Therefore I had a go on updating to the community-kernel-latest version 4.18.14-200.el7 which failed;
> > > Dracut could not (re)build a intitramfs-4.18.14-.. and (probably because of this) uInitrd-4.18.14-.. was missing to.
> > > Unfortunately did not write the exact error message down; next time will do so.
> > Does /boot have enough space?, I usually try to have 3 kernels at most.
> > I've been using that kernel in 3 different SoCs without problems, 
> > including Bananapi M3 (same SoC as the cubieboard5)
> 
> I do not doubt it had because it was the second kernel update done (i.e would be the 3rd installed)
> 
> However : just successfully installed  with a more conservative approach 4.17.17 > 4.18.9 > 4.18.14
> Side note is: this is on a home brew image without RPI bits and peaces, 786MB boot partition with ext4 file-system.
> In time I will try again with default Centos-Generic image.
> 
> i'm happy now:)
> cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor
> ondemand
> 
> > >
> > > BTW: Update to Kernel 4.17.17-200.el7 was successful on my oragngepi-plus2e
> > >
> > > In my own interest i'd really want to help to debug this;
> > > but to be able to do this i need to understand in more detail how we boot Centos on our u-boot based SBC's.
> > > I got the broad picture: u-boot >> extlinux bootloader >> kernel >>
> > Correct
> > > Getting lost however looking at extlinux/extlinux.conf , grub/grub.conf and not knowing the content of boot.scr
> > You can ignore grub.conf and boot.scr, extlinux.conf is all you need
> 
> Sorry to persist, I'd really like to understand in more detail;
> Questions circling in my head (among others)  are:
> Why do we have a uInitrd _and_ initramfs ?
> Why do we have a uimage _and_ vmlinux ?
> Why does my odroid HC1 boot with a Fedora image but not with Centos (kernel 4.14.71 nor 4.17.17)? (despite specific USB3 patches are backported to 4.14)
> 
> > >
> > > Can somebody enlighten me on this, or show me some further reading.
> > >
> > > (I did search fedora's arm documentation without getting smarter..)
> > >
> > > Actually in response to "Cubieboard5 performance"
> > > (https://lists.centos.org/pipermail/arm-dev/2018-October/003515.html)
> > >
> > >

Just a heads up, update to 4.18.16 works flawless on the above described setup on a oragngepi-plus2e.
Did not find the time to test it with a default img as I'm still in a fight with the odroid HC1.
For the latter the good new is: it's not an issue with the kernel but with the initramfs.