Kernel support for i.MX6UL and 4.9 LTS updates

Kernel support for i.MX6UL and 4.9 LTS updates

[jesse.gilles]

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Hello,

I am working on a project using the i.MX6UL and I am curious about the
state of Linux kernel support in various different kernel recipes in
meta-freescale.

After reading documentation and various posts, this is my understanding of
the different kernels in the layer:

linux-fslc: purely community maintained kernel, kept pretty up to date with
upstream
linux-imx-fslc: community maintained kernel, based off NXP official BSP
release kernel
linux-imx: NXP official BSP release kernel

For i.MX6UL support and functionality, is there a significant difference
between linux-fslc and linux-imx-fslc?

For linux-imx-fslc, is there a specific reason it is still using
4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?

If linux-imx-fslc is the best option, is anyone maintaining the 4.9 branch
and planning to keep it up to date with upstream LTS updates?  I see that
4.9-2.3.x-imx has been updated to 4.9.166.

In short, I am looking for the best maintained and updated kernel with
support for the i.MX6UL, including security fixes into the future.  My
existing project uses a customized linux-imx 4.9 kernel.

Any help would be greatly appreciated.

Thanks,
Jesse

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Fabio Estevam]

Hi Jesse,

On Thu, Dec 19, 2019 at 7:33 PM Jesse Gilles <jesse.gilles@gmail.com> wrote:
>
> Hello,
>
> I am working on a project using the i.MX6UL and I am curious about the state of Linux kernel support in various different kernel recipes in meta-freescale.
>
> After reading documentation and various posts, this is my understanding of the different kernels in the layer:
>
> linux-fslc: purely community maintained kernel, kept pretty up to date with upstream
> linux-imx-fslc: community maintained kernel, based off NXP official BSP release kernel
> linux-imx: NXP official BSP release kernel
>
> For i.MX6UL support and functionality, is there a significant difference between linux-fslc and linux-imx-fslc?
>
> For linux-imx-fslc, is there a specific reason it is still using 4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?
>
> If linux-imx-fslc is the best option, is anyone maintaining the 4.9 branch and planning to keep it up to date with upstream LTS updates?  I see that 4.9-2.3.x-imx has been updated to 4.9.166.
>
> In short, I am looking for the best maintained and updated kernel with support for the i.MX6UL, including security fixes into the future.  My existing project uses a customized linux-imx 4.9 kernel.
>
> Any help would be greatly appreciated.

I suggest you to move to kernel 5.4.x instead.

Regards,

Fabio Estevam

Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Jesse Gilles]

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Hi Fabio,

On Sat, Dec 21, 2019 at 6:11 AM Fabio Estevam <festevam@gmail.com> wrote:

>
> I suggest you to move to kernel 5.4.x instead.
>
>
Can you explain why you recommend the 5.4 kernel?  I don't see a recipe for
it in meta-freescale.

Can anyone else answer some of my other questions?

1. For i.MX6UL support and functionality, is there a significant difference
between linux-fslc and linux-imx-fslc?
2. For linux-imx-fslc, is there a specific reason it is still using
4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?
3. Is anyone maintaining the 4.9 branch and planning to keep it up to date
with upstream LTS updates?

Thanks,
Jesse

On Sat, Dec 21, 2019 at 6:11 AM Fabio Estevam <festevam@gmail.com> wrote:

> Hi Jesse,
>
> On Thu, Dec 19, 2019 at 7:33 PM Jesse Gilles <jesse.gilles@gmail.com>
> wrote:
> >
> > Hello,
> >
> > I am working on a project using the i.MX6UL and I am curious about the
> state of Linux kernel support in various different kernel recipes in
> meta-freescale.
> >
> > After reading documentation and various posts, this is my understanding
> of the different kernels in the layer:
> >
> > linux-fslc: purely community maintained kernel, kept pretty up to date
> with upstream
> > linux-imx-fslc: community maintained kernel, based off NXP official BSP
> release kernel
> > linux-imx: NXP official BSP release kernel
> >
> > For i.MX6UL support and functionality, is there a significant difference
> between linux-fslc and linux-imx-fslc?
> >
> > For linux-imx-fslc, is there a specific reason it is still using
> 4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?
> >
> > If linux-imx-fslc is the best option, is anyone maintaining the 4.9
> branch and planning to keep it up to date with upstream LTS updates?  I see
> that 4.9-2.3.x-imx has been updated to 4.9.166.
> >
> > In short, I am looking for the best maintained and updated kernel with
> support for the i.MX6UL, including security fixes into the future.  My
> existing project uses a customized linux-imx 4.9 kernel.
> >
> > Any help would be greatly appreciated.
>
> I suggest you to move to kernel 5.4.x instead.
>
> Regards,
>
> Fabio Estevam
>

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Clay Montgomery]

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Jesse,

     1. The best answer is probably to take a look at NXP's notes and 
defconfigs here:

     repo init -u 
https://source.codeaurora.org/external/imx/imx-manifest -b 
imx-linux-sumo -m imx-4.14.98-2.0.0_ga.xml

~/Yocto/imx-yocto-bsp/sources/meta-freescale/recipes-kernel/linux/

     2. There were a lot of changes made to the DRM in the 4.9 kernels 
that had a major impact on NXP's IPU and V4L2 support drivers. Some 
fundamental stuff (like /dev/fb, X11 and Wayland) were broken and NXP 
seems unlikely to ever fix that for newer kernels on the i.MX6.

     3. Certainly not NXP.

Most developers still on the i.MX6 seem to either stick with 4.1.15 or 
move to a mainline kernel.

Regards, Clay


On 1/3/2020 1:40 PM, Jesse Gilles wrote:
> Hi Fabio,
>
> On Sat, Dec 21, 2019 at 6:11 AM Fabio Estevam <festevam@gmail.com 
> <mailto:festevam@gmail.com>> wrote:
>
>
>     I suggest you to move to kernel 5.4.x instead.
>
>
> Can you explain why you recommend the 5.4 kernel?  I don't see a 
> recipe for it in meta-freescale.
>
> Can anyone else answer some of my other questions?
>
> 1. For i.MX6UL support and functionality, is there a significant 
> difference between linux-fslc and linux-imx-fslc?
> 2. For linux-imx-fslc, is there a specific reason it is still using 
> 4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?
> 3. Is anyone maintaining the 4.9 branch and planning to keep it up to 
> date with upstream LTS updates?
>
> Thanks,
> Jesse
>
> On Sat, Dec 21, 2019 at 6:11 AM Fabio Estevam <festevam@gmail.com 
> <mailto:festevam@gmail.com>> wrote:
>
>     Hi Jesse,
>
>     On Thu, Dec 19, 2019 at 7:33 PM Jesse Gilles
>     <jesse.gilles@gmail.com <mailto:jesse.gilles@gmail.com>> wrote:
>     >
>     > Hello,
>     >
>     > I am working on a project using the i.MX6UL and I am curious
>     about the state of Linux kernel support in various different
>     kernel recipes in meta-freescale.
>     >
>     > After reading documentation and various posts, this is my
>     understanding of the different kernels in the layer:
>     >
>     > linux-fslc: purely community maintained kernel, kept pretty up
>     to date with upstream
>     > linux-imx-fslc: community maintained kernel, based off NXP
>     official BSP release kernel
>     > linux-imx: NXP official BSP release kernel
>     >
>     > For i.MX6UL support and functionality, is there a significant
>     difference between linux-fslc and linux-imx-fslc?
>     >
>     > For linux-imx-fslc, is there a specific reason it is still using
>     4.9-1.0.x-imx and not the newer 4.9-2.3.x-imx branch?
>     >
>     > If linux-imx-fslc is the best option, is anyone maintaining the
>     4.9 branch and planning to keep it up to date with upstream LTS
>     updates?  I see that 4.9-2.3.x-imx has been updated to 4.9.166.
>     >
>     > In short, I am looking for the best maintained and updated
>     kernel with support for the i.MX6UL, including security fixes into
>     the future.  My existing project uses a customized linux-imx 4.9
>     kernel.
>     >
>     > Any help would be greatly appreciated.
>
>     I suggest you to move to kernel 5.4.x instead.
>
>     Regards,
>
>     Fabio Estevam
>
>
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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Fabio Estevam]

Hi Jesse,

On Fri, Jan 3, 2020 at 4:41 PM Jesse Gilles <jesse.gilles@gmail.com> wrote:

> Can you explain why you recommend the 5.4 kernel?  I don't see a recipe for it in meta-freescale.

5.4 kernel is the most recent kernel that will be LTS.

Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Jesse Gilles]

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Hi Clay, thanks very much for your answers.

On Fri, Jan 3, 2020 at 4:22 PM Clay Montgomery <clay@montgomery1.com> wrote:

> Jesse,
>
>     1. The best answer is probably to take a look at NXP's notes and
> defconfigs here:
>
>     repo init -u https://source.codeaurora.org/external/imx/imx-manifest
> -b imx-linux-sumo -m imx-4.14.98-2.0.0_ga.xml
>
>     ~/Yocto/imx-yocto-bsp/sources/meta-freescale/recipes-kernel/linux/
>
>     2. There were a lot of changes made to the DRM in the 4.9 kernels that
> had a major impact on NXP's IPU and V4L2 support drivers. Some fundamental
> stuff (like /dev/fb, X11 and Wayland) were broken and NXP seems unlikely to
> ever fix that for newer kernels on the i.MX6.
>
When you say that NXP is unlikely to fix IPU/video related driver support
in newer kernels, which kernel versions are you referring to?  Later
NXP-released 4.9 kernels like 4.9.123-2.3.0ga?

>     3. Certainly not NXP.
>
> Most developers still on the i.MX6 seem to either stick with 4.1.15 or
> move to a mainline kernel.
>
Do you know which mainline kernel version has full support for the i.MX6 or
how I would be able to find out the status of support in various kernel
versions?  If mainline is stable for the i.MX6 and the driver support is
on-par with the NXP-released kernels, I may considering moving to mainline
at some point.  I was under the assumption that mainline might be missing
critical driver support or bug fixes and I would be better off with an NXP
kernel, but perhaps that is not the case.

If developers stick with 4.1.15, how do they address kernel CVEs?  This is
the main issue I am concerned about.  I'm coming at this from a maintenance
and security perspective.  I need to be able to support shipping products
by providing fixes for any major CVEs and that includes the Linux kernel,
especially if any CVEs are remotely exploitable.  I would also like to do
this with the least impact possible, so avoiding major kernel upgrades is
preferable in my mind.

Can anyone comment on how they are handling kernel CVEs for products that
are i.MX-based?  Are you using a mainline LTS kernel and keeping up with
upstream updates?  Are you using an NXP kernel and manually patching
specific CVEs?

Thanks,
Jesse

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Richard Leitner]

Hi,

On 09/01/2020 16:13, Jesse Gilles wrote:
> Hi Clay, thanks very much for your answers. 
> 

...

> 
> Can anyone comment on how they are handling kernel CVEs for products that are i.MX-based?  Are you using a mainline LTS kernel and keeping up with upstream updates?  Are you using an NXP kernel and manually patching specific CVEs?

We're using the latest stable mainline kernel for different i.MX6 derivates.

For us everything (USB, ETH, SATA, MMC, I2C, CODA, HDMI, etc...) works with the mainline kernel.
Except the JPEG encoder which is currently under Patch review and will
hopefully be merged soon.

If you have any specific questions just ask ;-)

> 
> Thanks,
> Jesse
> 

regards;rl

Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Clay Montgomery]

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Jesse,

    I have inserted replies below...

On 1/9/2020 9:13 AM, Jesse Gilles wrote:
> Hi Clay, thanks very much for your answers.
>
> On Fri, Jan 3, 2020 at 4:22 PM Clay Montgomery <clay@montgomery1.com 
> <mailto:clay@montgomery1.com>> wrote:
>
>     Jesse,
>
>         1. The best answer is probably to take a look at NXP's notes
>     and defconfigs here:
>
>         repo init -u
>     https://source.codeaurora.org/external/imx/imx-manifest -b
>     imx-linux-sumo -m imx-4.14.98-2.0.0_ga.xml
>
>     ~/Yocto/imx-yocto-bsp/sources/meta-freescale/recipes-kernel/linux/
>
>         2. There were a lot of changes made to the DRM in the 4.9
>     kernels that had a major impact on NXP's IPU and V4L2 support
>     drivers. Some fundamental stuff (like /dev/fb, X11 and Wayland)
>     were broken and NXP seems unlikely to ever fix that for newer
>     kernels on the i.MX6.
>
> When you say that NXP is unlikely to fix IPU/video related driver 
> support in newer kernels, which kernel versions are you referring to?  
> Later NXP-released 4.9 kernels like 4.9.123-2.3.0ga?

I mean ALL kernels from 4.9.x onward.

Many developers are using newer kernels on the i.MX6, but they got there 
by going to mainline and either not using the VPU or GPUs at all, or 
using the open source Etnaviv drivers, which are limited in 
functionality (mainly OpenGL ES 3.0 and OpenCL stuff) compared to the 
Vivante package from NXP.

For example, if you build Yocto Sumo, Warrior or Thud from the FSL 
Community BSP, you get no functional VPU or GPU support. Even a lot of 
NXP's unit tests fail to run. Pyro is the latest one that works, because 
it has Vivante with 4.1.15 kernel.

Maybe someone has manually integrated a Vivante package with a mainline 
kernel themselves? But, that is likely a lot of work and undocumented. 
The issues are mainly with the DRM, I think. I would really like to see 
comments from anyone that has done that successfully, and what was required?

As far as NXP ever fixing this. They will not even reply about it:

https://community.nxp.com/thread/518771

>         3. Certainly not NXP.
>
>     Most developers still on the i.MX6 seem to either stick with
>     4.1.15 or move to a mainline kernel.
>
> Do you know which mainline kernel version has full support for the 
> i.MX6 or how I would be able to find out the status of support in 
> various kernel versions?  If mainline is stable for the i.MX6 and the 
> driver support is on-par with the NXP-released kernels, I may 
> considering moving to mainline at some point.  I was under the 
> assumption that mainline might be missing critical driver support or 
> bug fixes and I would be better off with an NXP kernel, but perhaps 
> that is not the case.
>
> If developers stick with 4.1.15, how do they address kernel CVEs?  
> This is the main issue I am concerned about. I'm coming at this from a 
> maintenance and security perspective.  I need to be able to support 
> shipping products by providing fixes for any major CVEs and that 
> includes the Linux kernel, especially if any CVEs are remotely 
> exploitable.  I would also like to do this with the least impact 
> possible, so avoiding major kernel upgrades is preferable in my mind.
>
> Can anyone comment on how they are handling kernel CVEs for products 
> that are i.MX-based?  Are you using a mainline LTS kernel and keeping 
> up with upstream updates?  Are you using an NXP kernel and manually 
> patching specific CVEs?
>
> Thanks,
> Jesse
>
>
I think the Vivante package (and DRM) is the big issue. The GPUs and VPU 
are maybe 30% of the i.MX6 quad die area.  That means it's 1/3 of the 
cost of the hardware, at least.

You are confusing the security needs of a desktop system with embedded. 
With embedded linux, kernel updates are not needed for good security if 
you configure the system well.

Regards, Clay


>
> 

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Jesse Gilles]

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On Thu, Jan 9, 2020 at 11:18 AM Clay Montgomery <clay@montgomery1.com>
wrote:

> I mean ALL kernels from 4.9.x onward.
>
> Many developers are using newer kernels on the i.MX6, but they got there
> by going to mainline and either not using the VPU or GPUs at all, or using
> the open source Etnaviv drivers, which are limited in functionality (mainly
> OpenGL ES 3.0 and OpenCL stuff) compared to the Vivante package from NXP.
>
> For example, if you build Yocto Sumo, Warrior or Thud from the FSL
> Community BSP, you get no functional VPU or GPU support. Even a lot of
> NXP's unit tests fail to run. Pyro is the latest one that works, because it
> has Vivante with 4.1.15 kernel.
>
> Maybe someone has manually integrated a Vivante package with a mainline
> kernel themselves? But, that is likely a lot of work and undocumented. The
> issues are mainly with the DRM, I think. I would really like to see
> comments from anyone that has done that successfully, and what was required?
>
> As far as NXP ever fixing this. They will not even reply about it:
>
> https://community.nxp.com/thread/518771
>

Thank you for the helpful detail.

You are confusing the security needs of a desktop system with embedded.
> With embedded linux, kernel updates are not needed for good security if you
> configure the system well.
>

Hm, I don't agree.  If an embedded Linux device uses Wi-Fi and Bluetooth
communications, won't vulnerabilities affecting those parts of the kernel
need to be patched?

Examples:
https://www.linuxkernelcves.com/cves/CVE-2019-17133
https://www.linuxkernelcves.com/cves/CVE-2019-16746
https://www.linuxkernelcves.com/cves/CVE-2019-9506

I believe some of these could be exploitable without accessing the device
or gaining local privileges.

Thanks,
Jesse

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Otavio Salvador]

On Thu, Jan 9, 2020 at 5:08 PM Jesse Gilles <jesse.gilles@gmail.com> wrote:
> On Thu, Jan 9, 2020 at 11:18 AM Clay Montgomery <clay@montgomery1.com> wrote:
> Hm, I don't agree.  If an embedded Linux device uses Wi-Fi and Bluetooth communications, won't vulnerabilities affecting those parts of the kernel need to be patched?
>
> Examples:
> https://www.linuxkernelcves.com/cves/CVE-2019-17133
> https://www.linuxkernelcves.com/cves/CVE-2019-16746
> https://www.linuxkernelcves.com/cves/CVE-2019-9506
>
> I believe some of these could be exploitable without accessing the device or gaining local privileges.

I agree with you Jesse and that's why we've been moving most of our
customers to Linux mainline. Most vendor BSP does not have stable
updates.

-- 
Otavio Salvador                             O.S. Systems
http://www.ossystems.com.br        http://code.ossystems.com.br
Mobile: +55 (53) 9 9981-7854          Mobile: +1 (347) 903-9750

Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Jesse Gilles]

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On Thu, Jan 9, 2020 at 9:28 AM Richard Leitner <richard.leitner@skidata.com>
wrote:

> We're using the latest stable mainline kernel for different i.MX6
> derivates.
>
> For us everything (USB, ETH, SATA, MMC, I2C, CODA, HDMI, etc...) works
> with the mainline kernel.
> Except the JPEG encoder which is currently under Patch review and will
> hopefully be merged soon.
>
> If you have any specific questions just ask ;-)
>

Thanks for the info.  Do you know if mainline 4.14.x contains adequate
support for the i.MX6UL?  4.14 appears to have the longest planned support
according to https://www.kernel.org/category/releases.html

Thanks,
Jesse

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Clay Montgomery]

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On 1/9/2020 2:14 PM, Otavio Salvador wrote:
> On Thu, Jan 9, 2020 at 5:08 PM Jesse Gilles <jesse.gilles@gmail.com> wrote:
>> On Thu, Jan 9, 2020 at 11:18 AM Clay Montgomery <clay@montgomery1.com> wrote:
>> Hm, I don't agree.  If an embedded Linux device uses Wi-Fi and Bluetooth communications, won't vulnerabilities affecting those parts of the kernel need to be patched?
>>
>> Examples:
>> https://www.linuxkernelcves.com/cves/CVE-2019-17133
>> https://www.linuxkernelcves.com/cves/CVE-2019-16746
>> https://www.linuxkernelcves.com/cves/CVE-2019-9506
>>
>> I believe some of these could be exploitable without accessing the device or gaining local privileges.
> I agree with you Jesse and that's why we've been moving most of our
> customers to Linux mainline. Most vendor BSP does not have stable
> updates.
>
It depends in your target application/market. If anyone can connect to 
your device with Wi-Fi or Bluetooth, then obviously security is a lot 
more important.

But, consider the digital signage player market, for example, where it's 
actually an advantage over Windows and Android devices to never require 
updates.

Regards, Clay


> 

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Re: [meta-freescale] Kernel support for i.MX6UL and 4.9 LTS updates

[Richard Leitner]

On 1/9/20 9:14 PM, Jesse Gilles wrote:
> 
> On Thu, Jan 9, 2020 at 9:28 AM Richard Leitner <richard.leitner@skidata.com <mailto:richard.leitner@skidata.com>> wrote:
> 
>     We're using the latest stable mainline kernel for different i.MX6 derivates.
> 
>     For us everything (USB, ETH, SATA, MMC, I2C, CODA, HDMI, etc...) works with the mainline kernel.
>     Except the JPEG encoder which is currently under Patch review and will
>     hopefully be merged soon.
> 
>     If you have any specific questions just ask ;-)
> 
> 
> Thanks for the info.  Do you know if mainline 4.14.x contains adequate support for the i.MX6UL?  4.14 appears to have the longest planned support according to https://www.kernel.org/category/releases.html

We've never tried 4.14. The last "LTS" version I used was 4.9.
Since then our strategy is to always use the latest stable version. Therefore
we are currently on 5.4 and will move to 5.5 in a few weeks.

This is due to known reasons which mainly derive from the kernels "every
fix has to be in master first" policy (or however it is really
called^^).

As we update our kernel regularly (especially in networked or physically
exposed solutions) it made no difference for us if we move to a new
stable release or LTS update.

Of course you should have an adequate test-depth to make sure nothing
breaks or other unwanted things (like a drop in performance) happens. ;-)

For more info on picking a kernel version I suggest reading Greg-KHs
blog on that: http://kroah.com/log/blog/2018/08/24/what-stable-kernel-should-i-use/

regards;rl

> Thanks, 
> Jesse