8.2: Modify kernel configuration
Hello,
I followed the steps in: https://wiki.centos.org/HowTos/Custom_Kernel The goal is to add CMA to the kernel and then install it. I'm quite sure I followed all steps including the ones listed in chapter 2: cd ~/rpmbuild/BUILD/kernel-*/linux-*/ cp /boot/config-`uname -r` .config make oldconfig make menuconfig add: # x86_64 cp .config configs/kernel-3.10.0-`uname -m`.config cp configs/* ~/rpmbuild/SOURCES/ Build new kernel: rpmbuild -bb --target=`uname -m` kernel.spec 2> build-err.log | tee build-out.log During the build, the modified .config was automatically changed back to its original version. The 3rd line is now: # Linux/x86_64 4.18.0-193.el8.cma.x86_64 Kernel Configuration cma is the buildid in my kernel.spec. but other changes I did in .config were gone. I ran the procedure few times to make sure I'm not missing a step. Each time I did it after installin centos 8.2 from scratch. In all trials, CMA was not added to the kernel. I checked it in /proc/meminfo Have anyone tried to install a custom centos 8.x kernel ? After booting the new kernel, I checked kernel-4.18.0-3.10.0-x86_64.config located in ~/rpmbuild/SOURCES It is the modified .config (CONFIG_CMA=y, CONFIG_DMA_CMA=y) Thank you, Zvika |
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https://www.linuxquestions.org/quest...er-4175695475/ https://www.linuxquestions.org/quest...-a-4175685514/ https://www.linuxquestions.org/quest...el-4175682807/ https://www.linuxquestions.org/quest...ng-4175671805/ https://www.linuxquestions.org/quest...ly-4175671763/ https://www.linuxquestions.org/quest...ct-4175669923/ https://www.linuxquestions.org/quest...-a-4175668757/ ...and the original CMA/kernel question, going back TWO YEARS, from the CentOS forums: https://forums.centos.org/viewtopic.php?t=71727 This is going on two years now...even more odd that you claim to have had it working already: https://www.linuxquestions.org/quest...7/#post6171022 You've not followed up in most of your threads here, but did you actually try to boot with the new kernel? And you keep alluding to embedded hardware, running a totally custom system, but don't tell us what this system is/does. |
Hello,
Non of the previous threads deal with the procedure in: https://wiki.centos.org/HowTos/Custom_Kernel According to the URL, it was tested on 7.x For example, the lines: Quote:
kernel.spec contains the right line (cp $RPM_SOURCE_DIR/kernel-*.config) Thank you, Zvika |
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You posted a link to the CentOS guide to build a kernel...what, exactly, do you think we're going to be able to add that isn't in the official documentation?? That was updated just a few months ago. If it doesn't match your system...you need to follow a different guide, don't you? And the part you say doesn't apply to 8...did you read step one carefully?? Since it says (bolded for emphasis only; partially bolded in original link/text): Quote:
And again, going back to at least last year, you were directed in another thread to read the Red Hat kernel notice that says explicitly: Quote:
You claim to have followed the instructions...yet on the CentOS forums, someone had to explicitly TELL YOU to follow some of the steps that you obviously didn't do: https://forums.centos.org/viewtopic....327075#p327075 ....so since you seemingly didn't follow the guide, chances are VERY good that you aren't going to have success. |
Hello,
In the default 8.2 installed from ISO, CMA is disabled. I must enable it. It is not clear from your answer what is the right procedure instead of the one listed in https://wiki.centos.org/HowTos/Custom_Kernel Do you mean that I should read the red hat procedure and not the one in the above URL ? BTW: In an older thread: https://www.linuxquestions.org/quest...el-4175682807/ I had the same issue. The "solution" I found there was to run: # make bzImage # make modules # make # make modules_install # make install This is not "by the book" way to modify kernel. Thank you, Zvika |
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Hello,
All I need is to enable CMA under centos 8.2. That's all. The hardware is : Lenovo ThinkSystem SR650 Server (Xeon SP Gen 2) It's not clear from your answer what is the right way to enable CMA on centos 8.2 The link I have is only: https://wiki.centos.org/HowTos/Custom_Kernel which fits only Centos 7 (am I right ?) You wrote: "You claim to have followed the instructions...yet on the CentOS forums, someone had to explicitly TELL YOU to follow some of the steps that you obviously didn't do: https://forums.centos.org/viewtopic....327075#p327075" Those steps were completed successfully. But the final goal (CMA enabled) was failed. Thank you, Zvika |
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Since CentOS 8 is NOT CentOS 7, what do you think you should do?? Quote:
AGAIN: you have been working on 'enabling CMA' for two years now; you claim to have done it before as well. Have you actually read up on what's needed, also? Because again, you were pointed to the runtime kernel switches you need to put in, to enable things. Kernel parameters: Code:
CONFIG_CMA=y Code:
cma=<SOME MEMORY SIZE> |
Hello,
About 2 years ago I used the procedure listed in: https://www.tecmint.com/compile-linu...l-on-centos-7/ I'm quite sure this procedure is not recommended by Centos in: https://wiki.centos.org/HowTos/Custom_Kernel According to the guide: "If you you do not intend to modify the distributed kernel configuration file you may omit this section (CentOS-7)" I want to modify kernel configuration, so how should I change kernel configuration for 8.2 ? Thank you, Zvika |
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You have been told, SEVERAL TIMES, to use the CentOS guide; THAT IS HOW YOU DO IT. Cannot be more plain and simple. If you cannot understand that, there is NOTHING we can do to help you. AGAIN: follow that guide..it is clear you have not, or just do not understand how to do it. So far:
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Hello,
In the centos manual I found one mistake: [user@host]$ cp .config configs/kernel-3.10.0-`uname -m`.config Should be: cp .config configs/kernel-4.18.0-x86_64.config (for 8.2 only) So it seems the manual was not fully adapted to 8.2 yet. This change did not help also. After installing the new RPMs, in /boot I got config without my changes. Thank you, Zvika |
When you did 'make menuconfig' did you make the appropriate changes for CMA and save it to .config before exiting out?
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Hello,
Following are the steps I'm doing: Quote:
the folder configs contains also the file: kernel-4.18.0-x86_64.config I double checked: This file contains CMA=y + DMA_CMA=y Can you please tell what is wrong in my steps ? Thank you, Zvika |
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