Linux kernel on STM32MP157F

[OBaselga]

Hi,

I am using the STM32MP157F-DK2 MPU for a Linux project. Exactly, I am interested in Linux-RT. Browsing in the Internet, it is said that only is necessary applying a patch in the kernel. The patch file uses the command "git diff", but is not installed in the kernel.

My goal is install it, however, "apt" is not either installed, so I have to make the install with "dpkg" - something completely caotic.

HELP! Is there any way to install "apt" or "yum"? If not, how can I install "git" command so that applying the patch?

Thanks,

Oscar

[Olivier GALLIEN · Accepted solution]

Hi @Óscar Baselga​ ,

Thanks for your post.

First, I warn you that ST does not guarantee and will not support the STM32MP1 product with Linux-RT configuration.

Second, moving to Linux-RT imply one kernel option with several patches.

I don't get your point related to "apt", "git" and "yum" ? Do you expect to do it on a running target ?

AFAIK it's not possible. You should use developer or Distribution package and manage to update your kernel from HOST machine :

https://wiki.st.com/stm32mpu/wiki/How_to_cross-compile_with_the_Developer_Package

https://wiki.st.com/stm32mpu/wiki/How_to_cross-compile_with_the_Distribution_Package

https://wiki.st.com/stm32mpu/wiki/Menuconfig_or_how_to_configure_kernel

Hope it help,

Olivier

[Olivier GALLIEN]

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[OBaselga]

Hi Oliver,

About not supporting Linux-RT, I read this post: https://community.st.com/s/question/0D50X0000C4P4muSQC/preempt-rt-patch-for-openstlinux , where they said that it works at first sight. Anyway, although it isn't guaranteed, could it work?

On the other hand, I meant that I was using "screen" linux command in order that accessing STM32MP1. Once there, I pretended to install "git" command because the patch I had downloaded - for changing the kernel version to RT - used it. I see that I must do the update from host, I'll try it.

Thank you for your answer,

Oscar

[Olivier GALLIEN]

Hi @Óscar Baselga​ ,

I have to mitigate my initial statement.

Actually we have sanity checked OpenSTLinux with kernel5.10 and PREEMPT_RT kernel config.

But NOT with the full Linux RT patches on top.

Indeed, this does not state it's not working, but only that this can lead to unpredictable behavior.

Olivier

[OBaselga]

Hi Olivier,

Sorry for the confusion, but like you can appreciate I am new in Linux RT. Which is the difference between "PREEMPT_RT kernel config" and " full Linux RT"? I thought that if you achieved to set "PREEMPT_RT", Linux RT would be set.

Thanks,

Oscar

[Olivier GALLIEN]

Hi @Óscar Baselga​ ,

Well I cannot really help further. I think you should better find support from Linux community itself.

But since you are not Linux RT expert, why are you investigating this direction ?

I remind you that STM32MP15 has been design with a M4 coprocessor precisely to host real-time process and avoid need of Linux-RT in most case.

Olivier

[OBaselga]

Hi Olivier,

I only wanted to implement a hard real time system with Linux - for using some libraries. Could STM32MP1 support these requisites?

I thought I would need Linux-RT for that.

Oscar