Kernel compilation walk-through

Tim Giles schrieb:

 

It takes about 10 hours so let it run overnight.

That's only one side of the truth. Do you know how to cross-compile a kernel. It takes me on an 8 core about 10 minutes!

Take a look at

http://elinux.org/Raspberry_Pi_Kernel_Compilation#2._Cross_compiling_from_Linux

and have fun.

If there's someone who likes to install a precompiled kernel in deb-format  (DOES NOT WORK FOR Raspberry Pi 2! ) ->

https://blog.georgmill.de/2015/02/18/update-for-wolfson-audio-card-on-raspberry-pi/

That's only one side of the truth. Do you know how to cross-compile a kernel. It takes me on an 8 core about 10 minutes!

That's an incomplete truth.  It's a false generalization that's based upon the assumption that everyone uses a debian-type 32-bit compatible linux system.  Now that we're in the 21st Century, the world is full of 64-bit only installations and those boxes aren't going to result in a make that requires only 10-minutes of seat time.

If a user happens to be running something like 32-bit Ubuntu on an 8-core box then he might succeed in a 10-minute 8-core make.  In that case, things will probably "just work" because as a matter of coincidence he happens to be running a backward-compatible system on the same type of backward-compatible platform as the guy who wrote the incomplete set of cross-compiling instructions that are tailored to that type of platform.  Try cross compiling a 32-bit deb target using a 64-bit-only RPM-based system and let us know how that works out.  There will be far less seat-time and a lot less frustration required if you compile natively on the Pi and let it run overnight.

I've been building linux from source code for ~15 years.  I have my own 40-core distributed compiling farm.  I have enough experience with cross-compiling under distcc that I understand the pitfalls of cross-compiling, and that it's a bad idea to blindly recommend cross-compiling for everyone.  If a n00b is interested in compiling a kernel for the first time, I'd want to know exactly what kind of environment they're working in before making a recommendation that involved cross-compiling.  Cross-compiling can be fraught with errors while compiling in the native environment is simple by comparison.  Personally, I think that the recommendation to compile on the native platform is a more responsible recommendation to make, irrespective of how much wall-clock-time may be involved.

In the big scheme of things, how much wall-clock-time it takes to compile a kernel isn't really relevant.  It's only relevant to someone who is intent on staring at the monitor and watching everything happen in real-time.

I think that Tim is doing the community a great service by posting foolproof instructions on how to perform a native compile on the Raspberry Pi.  IMO too many guides offer only cross-compiling instructions, which I think is irresponsible and short-sighted.  I would not consider recommending cross-compiling until after I had performed the due diligence required to ensure that such a recommendation would work properly on the user's system.  Anything less amounts to a bum steer.

Thanks for posting this, Tim.

That's only one side of the truth. Do you know how to cross-compile a kernel. It takes me on an 8 core about 10 minutes!

That's an incomplete truth.  It's a false generalization that's based upon the assumption that everyone uses a debian-type 32-bit compatible linux system.  Now that we're in the 21st Century, the world is full of 64-bit only installations and those boxes aren't going to result in a make that requires only 10-minutes of seat time.

If a user happens to be running something like 32-bit Ubuntu on an 8-core box then he might succeed in a 10-minute 8-core make.  In that case, things will probably "just work" because as a matter of coincidence he happens to be running a backward-compatible system on the same type of backward-compatible platform as the guy who wrote the incomplete set of cross-compiling instructions that are tailored to that type of platform.  Try cross compiling a 32-bit deb target using a 64-bit-only RPM-based system and let us know how that works out.  There will be far less seat-time and a lot less frustration required if you compile natively on the Pi and let it run overnight.

I've been building linux from source code for ~15 years.  I have my own 40-core distributed compiling farm.  I have enough experience with cross-compiling under distcc that I understand the pitfalls of cross-compiling, and that it's a bad idea to blindly recommend cross-compiling for everyone.  If a n00b is interested in compiling a kernel for the first time, I'd want to know exactly what kind of environment they're working in before making a recommendation that involved cross-compiling.  Cross-compiling can be fraught with errors while compiling in the native environment is simple by comparison.  Personally, I think that the recommendation to compile on the native platform is a more responsible recommendation to make, irrespective of how much wall-clock-time may be involved.

In the big scheme of things, how much wall-clock-time it takes to compile a kernel isn't really relevant.  It's only relevant to someone who is intent on staring at the monitor and watching everything happen in real-time.

I think that Tim is doing the community a great service by posting foolproof instructions on how to perform a native compile on the Raspberry Pi.  IMO too many guides offer only cross-compiling instructions, which I think is irresponsible and short-sighted.  I would not consider recommending cross-compiling until after I had performed the due diligence required to ensure that such a recommendation would work properly on the user's system.  Anything less amounts to a bum steer.

Thanks for posting this, Tim.