[Arm-dev] unable to configure zram-swap on RPI 4 8G model (32bit)

Sun Jan 24 12:59:15 UTC 2021
Pablo Sebastián Greco <pablo at fliagreco.com.ar>

On 19/1/21 10:36, mark wrote:
> -----Original message-----
>> From: mark <mark at havak.nl>
>> Sent: Thursday December 17th, 2020 22:10
>> To: Pablo Sebastián Greco <pablo at fliagreco.com.ar>; Conversations around CentOS on ARM hardware <arm-dev at centos.org>
>> Subject: RE: [Arm-dev] unable to configure zram-swap on RPI 4 8G model (32bit)
>>
>> -----Original message-----
>>> From: Pablo Sebastián Greco <pablo at fliagreco.com.ar>
>>> Sent: Thursday, December 17, 2020 9:39 PM
>>> To: mark <mark at havak.nl>; Conversations around CentOS on ARM hardware <arm-dev at centos.org>
>>> Subject: Re: [Arm-dev] unable to configure zram-swap on RPI 4 8G model (32bit)
>>>
>>>
>>> On 17/12/20 14:09, mark wrote:
>>>> -----Original message-----
>>>>> From: mark <mark at havak.nl>
>>>>> Sent: Monday, December 14, 2020 6:15 PM
>>>>> To: Pablo Sebastián Greco <pablo at fliagreco.com.ar>; Conversations around
>>> CentOS on ARM hardware <arm-dev at centos.org>
>>>>> Subject: RE: [Arm-dev] unable to configure zram-swap on RPI 4 8G model
>>> (32bit)
>>>>>
>>>>>
>>>>> -----Original message-----
>>>>>> From: Pablo Sebastián Greco <pablo at fliagreco.com.ar>
>>>>>> Sent: Monday, December 14, 2020 6:00 PM
>>>>>> To: Conversations around CentOS on ARM hardware <arm-dev at centos.org>;
>>> mark
>>>>> <mark at havak.nl>
>>>>>> Subject: Re: [Arm-dev] unable to configure zram-swap on RPI 4 8G model
>>> (32bit)
>>>>>>
>>>>>> On 14/12/20 13:43, mark wrote:
>>>>>>> -----Original Message-----
>>>>>>> From: Pablo Sebastián Greco <pablo at fliagreco.com.ar>
>>>>>>> Sent: maandag 14 december 2020 17:20
>>>>>>> To: Conversations around CentOS on ARM hardware <arm-dev at centos.org>;
>>>>> mark
>>>>>> <mark at havak.nl>
>>>>>>> Subject: Re: [Arm-dev] unable to configure zram-swap on RPI 4 8G model
>>>>> (32bit)
>>>>>>> On 14/12/20 11:42, mark wrote:
>>>>>>>> Being aware using zram-swap is not a default feature  on the CentOS
>>>>>>>> Userland for armv7hl, Still want to share the problem I ran in to.
>>>>>>>>
>>>>>>>> I turns out the arm 32bit kernel with large memory support OOPS if
>> zram-swap
>>>>>> is deployed if the system has more than 4GB ram.
>>>>>>> I'm a heavy user of zram-swap, even not being default, but I have only
>>>>> used
>>>>>> with devices that have 2G max, this is interesting. Does it still happen
>>>>> if
>>>>>> you limit the size?
>>>>>>> Did not test limiting the ram to 4GB myself jet, it does according
>> to
>>>>> :
>>>>>>> https://github.com/raspberrypi/linux/issues/3839#issuecomment-723027652
>>>>>> I meant limiting the size of the zram-swap
>>>>> No the size of the swap does not seem matter: I tried 512, 1024 and 4096MB
>>>>>
>>>>> On a RPI4 4GB model it works just fine,
>>>>> on a 8GB model I get a "Internal error: Oops: 207"
>>>>>
>>>>> BTW running a fresh homebrew image of CentOS 7.9.2009 without a swap-partition
>>>>> and kernel:
>>>>> 5.4.72-v7l.1.el7 #1 SMP Wed Oct 21 17:20:56 UTC 2020 armv7l armv7l armv7l
>>>>> GNU/Linux
>>>>>
>>>>>
>>>>>>>> This issue seems to be addressed (very recently) in kernel 5.4.81
>> (1)
>>>>>>>> As mentioned this is very recently, version 5.4.81 is just 12 day's
>>>>> old..
>>>>>>>> However if there is a testbuild of this rpi2-kernel4: I'm eager to
>> test
>>>>>> it 
>>>> Just a heads-up,
>>>>
>>>> I could not figure out how to make a test build of a kernel => 5.4.81
>> based
>>> on the current raspberrypi2-kernel4-5.4.72 kernel.
>>>> Not knowledgeable enough to update the rpi-5.4.x.patch... My Bad
>>>>
>>>> However was able to rebuild the current kernel with the patch mentioned
>>> in the commit (1);
>>>> needed to include an other, quite harmless looking, patch in order to
>> get
>>> it applied clean
>>>
>>> That's even better actually, because we can confirm that it actually
>>> that patch that fixes it, thanks!!!
>>>
>>> Just curious, how long did it take to rebuild the kernel?
>> About 01:45; (mock) state.log building on an odroid hc1:
>>
>> 2020-12-17 15:46:56,190 - Mock Version: 2.7
>> 2020-12-17 15:46:58,637 - Start: yum update
>> 2020-12-17 15:47:11,414 - Finish: yum update
>> 2020-12-17 15:47:11,458 - Finish: chroot init
>> 2020-12-17 15:47:11,470 - Start: build phase for raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 15:47:11,488 - Start: build setup for raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 15:48:41,143 - Finish: build setup for raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 15:48:41,147 - Start: Outputting list of installed packages
>> 2020-12-17 15:48:41,842 - Finish: Outputting list of installed packages
>> 2020-12-17 15:48:41,843 - Start: rpmbuild raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 17:28:49,731 - Finish: rpmbuild raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 17:28:51,856 - Finish: build phase for raspberrypi2-5.4.72-v7.1.1.ns7.src.rpm
>> 2020-12-17 17:28:51,884 - Start: clean chroot
>> 2020-12-17 17:30:32,678 - Finish: clean chroot
>> 2020-12-17 17:30:32,683 - Finish: run
>>
>> probably going to move to a (faster) platform in the future;
>> it is hard to just say goodbye to a device that served you well :)
>>
>>>> Long story short, zram-swap works on my RPI4 8G model:
>>>>
>>>> # swapon --show
>>>> NAME       TYPE      SIZE USED PRIO
>>>> /dev/zram0 partition 3.7G   0B   -2
>>>>
>>>> # uname -a
>>>> Linux localhost 5.4.72-v7l.1.1.el7 #1 SMP Thu Dec 17 16:13:03 CET 2020
>> armv7l
>>> armv7l armv7l GNU/Linux
>>>> # free -m
>>>>                  total        used        free      shared  buff/cache
>> available
>>>> Mem:           7876          94        7469          16         312
>>> 7691
>>>> Swap:          3755           0        3755
>>>>
>>>>
>>>> In my (probably short lived) git repo the changes I made:
>>>> https://github.com/markVnl/Centos-raspberrypi2-kernel/tree/zram-swap-oops
>>>>
>>>>
>>>>>>> There's no test build yet, I'm still adjusting to what happened last
>>>>>>> week, but hopefully we'll have a new kernel soon
> Hi, is there a status update on this?
>
> Did run your test build (5.4.84-v8.1.el7.armhfp) from buildlogs it solved the issue
> and just saw (as in now) a build of 5.4.88-v8.1.el7.armhfp, wil test that one too
For some reason, those kernels were built but not released. I think 
Johhny finally pushed them a few days ago
>>>>>>>> 1) https://github.com/raspberrypi/linux/commit/1bef5f25a69234613b92a0e2456870fee4a57efc
>>>>>>>>
>>>>>>>>      
>>>>>>> Pablo.
>>>>>>>
>>>>>>> _______________________________________________
>>>>>>> Arm-dev mailing list
>>>>>>> Arm-dev at centos.org
>>>>>>> https://lists.centos.org/mailman/listinfo/arm-dev
>>> Pablo.
>>>
Pablo