What is the fastest way to build and boot a kernel

What is the fastest way to build and boot a kernel

[Code Soldier1]

Hi,

Can someone suggest what is the fastest way to build a minimal kernel
and boot. For example if I am working on TCP and would like to make a
small change and reboot, what is the fastest way, I rather not build
the whole kernel.

Thanks

-- 
CS1

What is the fastest way to build and boot a kernel

[Greg KH]

On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
> Hi,
> 
> Can someone suggest what is the fastest way to build a minimal kernel
> and boot. For example if I am working on TCP and would like to make a
> small change and reboot, what is the fastest way, I rather not build
> the whole kernel.

Why would you need to rebuild the whole kernel?  What did you change
that required everything to be rebuilt?

And a working kernel can normally be built, from scratch, in just a few
minutes.  You do know about 'make localmodconfig' right?

thanks,

greg k-h

What is the fastest way to build and boot a kernel

[Code Soldier1]

Hi Greg,

No I did not know about 'make localmodconfig'. Can you kindly explain.
As far as the change is concerned I am planning to change a few things
and experiment, so there is nothing specific.

Thanks,

On Tue, Apr 18, 2017 at 9:07 AM, Greg KH <greg@kroah.com> wrote:
> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>> Hi,
>>
>> Can someone suggest what is the fastest way to build a minimal kernel
>> and boot. For example if I am working on TCP and would like to make a
>> small change and reboot, what is the fastest way, I rather not build
>> the whole kernel.
>
> Why would you need to rebuild the whole kernel?  What did you change
> that required everything to be rebuilt?
>
> And a working kernel can normally be built, from scratch, in just a few
> minutes.  You do know about 'make localmodconfig' right?
>
> thanks,
>
> greg k-h



-- 
CS1

What is the fastest way to build and boot a kernel

[Peter Senna Tschudin]

On Tue, Apr 18, 2017 at 7:38 PM, Code Soldier1 <codesoldier1@gmail.com> wrote:
> Hi Greg,
>
> No I did not know about 'make localmodconfig'. Can you kindly explain.
> As far as the change is concerned I am planning to change a few things
> and experiment, so there is nothing specific.

Check this out:

https://lwn.net/Articles/660404/

>
> Thanks,
>
> On Tue, Apr 18, 2017 at 9:07 AM, Greg KH <greg@kroah.com> wrote:
>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>>> Hi,
>>>
>>> Can someone suggest what is the fastest way to build a minimal kernel
>>> and boot. For example if I am working on TCP and would like to make a
>>> small change and reboot, what is the fastest way, I rather not build
>>> the whole kernel.
>>
>> Why would you need to rebuild the whole kernel?  What did you change
>> that required everything to be rebuilt?
>>
>> And a working kernel can normally be built, from scratch, in just a few
>> minutes.  You do know about 'make localmodconfig' right?
>>
>> thanks,
>>
>> greg k-h
>
>
>
> --
> CS1
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies



-- 
Peter

What is the fastest way to build and boot a kernel

[Greg KH]

On Tue, Apr 18, 2017 at 10:38:52AM -0700, Code Soldier1 wrote:
> Hi Greg,
> 
> No I did not know about 'make localmodconfig'. Can you kindly explain.

Did you look at the help in the kernel makefile:

	make help
will show you what the different options do.

localmodconfig makes a kernel configuration based on your system and the
modules loaded, which is much smaller than the "full distribution"
kernel build, for all hardware in the world, which you don't usually
want for your own development.

There's also a whole book, free online, Linux Kernel in a Nutshell, that
describes how to configure, build, and boot a custom kernel, that might
help you out.

> As far as the change is concerned I am planning to change a few things
> and experiment, so there is nothing specific.

Then experiment away and see how it goes!

good luck,

greg k-h

What is the fastest way to build and boot a kernel

[Code Soldier1]

Thanks a lot Greg and Peter.

On Tue, Apr 18, 2017 at 10:44 AM, Greg KH <greg@kroah.com> wrote:
> On Tue, Apr 18, 2017 at 10:38:52AM -0700, Code Soldier1 wrote:
>> Hi Greg,
>>
>> No I did not know about 'make localmodconfig'. Can you kindly explain.
>
> Did you look at the help in the kernel makefile:
>
>         make help
> will show you what the different options do.
>
> localmodconfig makes a kernel configuration based on your system and the
> modules loaded, which is much smaller than the "full distribution"
> kernel build, for all hardware in the world, which you don't usually
> want for your own development.
>
> There's also a whole book, free online, Linux Kernel in a Nutshell, that
> describes how to configure, build, and boot a custom kernel, that might
> help you out.
>
>> As far as the change is concerned I am planning to change a few things
>> and experiment, so there is nothing specific.
>
> Then experiment away and see how it goes!
>
> good luck,
>
> greg k-h



-- 
CS1

What is the fastest way to build and boot a kernel

[Guru Das S]

On 18 April 2017 at 11:04, Code Soldier1 <codesoldier1@gmail.com> wrote:
> Thanks a lot Greg and Peter.
Hello,

Top-posting is frowned upon in the Linux Kernel mailing lists. Please
use the interleaved style instead, as described in this Wikipedia
article: https://en.wikipedia.org/wiki/Posting_style#Placement_of_replies

> On Tue, Apr 18, 2017 at 10:44 AM, Greg KH <greg@kroah.com> wrote:
>> On Tue, Apr 18, 2017 at 10:38:52AM -0700, Code Soldier1 wrote:
>>> Hi Greg,
>>>
>>> No I did not know about 'make localmodconfig'. Can you kindly explain.
>>
>> Did you look at the help in the kernel makefile:
>>
>>         make help
>> will show you what the different options do.
>>
>> localmodconfig makes a kernel configuration based on your system and the
>> modules loaded, which is much smaller than the "full distribution"
>> kernel build, for all hardware in the world, which you don't usually
>> want for your own development.
>>
>> There's also a whole book, free online, Linux Kernel in a Nutshell, that
>> describes how to configure, build, and boot a custom kernel, that might
>> help you out.
>>
>>> As far as the change is concerned I am planning to change a few things
>>> and experiment, so there is nothing specific.
>>
>> Then experiment away and see how it goes!
>>
>> good luck,
>>
>> greg k-h
>

To add to what Greg said, disabling the staging drivers config option
in the .config file speeds up the entire process. To do this, just
comment out the CONFIG_STAGING line in that file.

>
>
> --
> CS1
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

Guru Das Srinagesh.

What is the fastest way to build and boot a kernel

[Manoj]

Code Soldier1 writes:

> Hi,
>
> Can someone suggest what is the fastest way to build a minimal kernel
> and boot. For example if I am working on TCP and would like to make a
> small change and reboot, what is the fastest way, I rather not build
> the whole kernel.
>
> Thanks

FWIW, check this out if you want to have a setup to make
incremental changes to your kernel and test them out quickly.
It describes a quick and easy setup to test kernel changes on an
emulator without acutally rebooting your machine (helps with initial
testing)

http://www.mycpu.org/kernel-n00b-howto/

I use this setup for testing out small/quick changes. As mentioned
earlier in this thread, compilation for incremental changes should not
take long.

HTH.

-- 
Manoj

What is the fastest way to build and boot a kernel

[Tobin C. Harding]

On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
[snip]

Why the moniker?

What is the fastest way to build and boot a kernel

[valdis.kletnieks at vt.edu]

On Wed, 19 Apr 2017 20:32:31 +1000, "Tobin C. Harding" said:
> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
> [snip]
>
> Why the moniker?

Could be worse. "Code Cannon Fodder", for example....
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What is the fastest way to build and boot a kernel

[Aruna Hewapathirane]

>> On Wed, Apr 19, 2017 at 6:49 AM, <valdis.kletnieks@vt.edu> wrote:
>> On Wed, 19 Apr 2017 20:32:31 +1000, "Tobin C. Harding" said:
>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>> [snip]
>>
>> Why the moniker?

>>Could be worse. "Code Cannon Fodder", for example....

And this is what happens when you slap the code with a flying trout:
https://paste.debian.net/928354/

Pay attention to the build times. Yes this is a pre-compiled kernel but
that last build was 0m3.720s which I think we can safely say is fast enough
for most of us :)
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What is the fastest way to build and boot a kernel

[Code Soldier1]

On Wed, Apr 19, 2017 at 3:32 AM, Tobin C. Harding <me@tobin.cc> wrote:
> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
> [snip]
>
> Why the moniker?

Why not ? unlike most people today I value my privacy.

-- 
CS1

What is the fastest way to build and boot a kernel

[Sébastien Masson]

On 2017-04-19 20:26, Code Soldier1 wrote:
> On Wed, Apr 19, 2017 at 3:32 AM, Tobin C. Harding <me@tobin.cc> wrote:
>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>> [snip]
>> 
>> Why the moniker?
> 
> Why not ? unlike most people today I value my privacy.

Hi!

In my opinion, the point is not really about privacy.  Although, I 
understand you concern.

As a kernel developer, the source code you will write will be subject to 
copyright matters and, if you want to contribute, you will have to give 
your agreement to this.
This is only possible using your real name.

I am inviting you to read: Documentation/process/submitting-patches.rst 
in this regard.

Of course, as long as you do not submit source code, it does not really 
matter.  It may be more a question of "consistency".

BR,
Sebastien.

What is the fastest way to build and boot a kernel

[Code Soldier1]

On Thu, Apr 20, 2017 at 1:21 AM, S?bastien Masson
<sebastien@masson.engineer> wrote:
>
> On 2017-04-19 20:26, Code Soldier1 wrote:
>>
>> On Wed, Apr 19, 2017 at 3:32 AM, Tobin C. Harding <me@tobin.cc> wrote:
>>>
>>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>>> [snip]
>>>
>>> Why the moniker?
>>
>>
>> Why not ? unlike most people today I value my privacy.
>
>
> Hi!
>
> In my opinion, the point is not really about privacy.  Although, I
> understand you concern.
>
> As a kernel developer, the source code you will write will be subject to
> copyright matters and, if you want to contribute, you will have to give your
> agreement to this.
> This is only possible using your real name.
>
> I am inviting you to read: Documentation/process/submitting-patches.rst in
> this regard.
>
> Of course, as long as you do not submit source code, it does not really
> matter.  It may be more a question of "consistency".
>
> BR,
> Sebastien.

I completely agree with you. If I decide to submit code and there is a
requirement, I will have to make a choice. BTW how would anyone verify
if I am really Joe Smith and I have not just created an email account
?

I just looked at the kernel that I am working with and it does not
have the file you pointed out to me. I read the first file and it does
not say anything about username neither did anyone objected when I
posted on netdev.

ubuntu-server:~/linux/linux-stable-v4.9.9/Documentation$ find . -name
\*patches\* -print
./hwmon/submitting-patches
./applying-patches.txt
./devicetree/bindings/submitting-patches.txt




-- 
CS1

What is the fastest way to build and boot a kernel

[Alexander Kapshuk]

On Thu, Apr 20, 2017 at 7:20 PM, Code Soldier1 <codesoldier1@gmail.com> wrote:
> On Thu, Apr 20, 2017 at 1:21 AM, S?bastien Masson
> <sebastien@masson.engineer> wrote:
>>
>> On 2017-04-19 20:26, Code Soldier1 wrote:
>>>
>>> On Wed, Apr 19, 2017 at 3:32 AM, Tobin C. Harding <me@tobin.cc> wrote:
>>>>
>>>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>>>> [snip]
>>>>
>>>> Why the moniker?
>>>
>>>
>>> Why not ? unlike most people today I value my privacy.
>>
>>
>> Hi!
>>
>> In my opinion, the point is not really about privacy.  Although, I
>> understand you concern.
>>
>> As a kernel developer, the source code you will write will be subject to
>> copyright matters and, if you want to contribute, you will have to give your
>> agreement to this.
>> This is only possible using your real name.
>>
>> I am inviting you to read: Documentation/process/submitting-patches.rst in
>> this regard.
>>
>> Of course, as long as you do not submit source code, it does not really
>> matter.  It may be more a question of "consistency".
>>
>> BR,
>> Sebastien.
>
> I completely agree with you. If I decide to submit code and there is a
> requirement, I will have to make a choice. BTW how would anyone verify
> if I am really Joe Smith and I have not just created an email account
> ?
>
> I just looked at the kernel that I am working with and it does not
> have the file you pointed out to me. I read the first file and it does
> not say anything about username neither did anyone objected when I
> posted on netdev.
>
> ubuntu-server:~/linux/linux-stable-v4.9.9/Documentation$ find . -name
> \*patches\* -print
> ./hwmon/submitting-patches
> ./applying-patches.txt
> ./devicetree/bindings/submitting-patches.txt
>
>
>
>
> --
> CS1
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies

https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/plain/Documentation/SubmittingPatches?id=refs/tags/v4.9.23

11) Sign your work
------------------

To improve tracking of who did what, especially with patches that can
percolate to their final resting place in the kernel through several
layers of maintainers, we've introduced a "sign-off" procedure on
patches that are being emailed around.

The sign-off is a simple line at the end of the explanation for the
patch, which certifies that you wrote it or otherwise have the right to
pass it on as an open-source patch.  The rules are pretty simple: if you
can certify the below:

Developer's Certificate of Origin 1.1
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

By making a contribution to this project, I certify that:

        (a) The contribution was created in whole or in part by me and I
            have the right to submit it under the open source license
            indicated in the file; or

        (b) The contribution is based upon previous work that, to the best
            of my knowledge, is covered under an appropriate open source
            license and I have the right under that license to submit that
            work with modifications, whether created in whole or in part
            by me, under the same open source license (unless I am
            permitted to submit under a different license), as indicated
            in the file; or

        (c) The contribution was provided directly to me by some other
            person who certified (a), (b) or (c) and I have not modified
            it.

        (d) I understand and agree that this project and the contribution
            are public and that a record of the contribution (including all
            personal information I submit with it, including my sign-off) is
            maintained indefinitely and may be redistributed consistent with
            this project or the open source license(s) involved.

then you just add a line saying::

Signed-off-by: Random J Developer <random@developer.example.org>

using your real name (sorry, no pseudonyms or anonymous contributions.)

What is the fastest way to build and boot a kernel

[Joe Smith]

On Thu, Apr 20, 2017 at 9:31 AM, Alexander Kapshuk
<alexander.kapshuk@gmail.com> wrote:
> On Thu, Apr 20, 2017 at 7:20 PM, Code Soldier1 <codesoldier1@gmail.com> wrote:
>> On Thu, Apr 20, 2017 at 1:21 AM, S?bastien Masson
>> <sebastien@masson.engineer> wrote:
>>>
>>> On 2017-04-19 20:26, Code Soldier1 wrote:
>>>>
>>>> On Wed, Apr 19, 2017 at 3:32 AM, Tobin C. Harding <me@tobin.cc> wrote:
>>>>>
>>>>> On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
>>>>> [snip]
>>>>>
>>>>> Why the moniker?
>>>>
>>>>
>>>> Why not ? unlike most people today I value my privacy.
>>>
>>>
>>> Hi!
>>>
>>> In my opinion, the point is not really about privacy.  Although, I
>>> understand you concern.
>>>
>>> As a kernel developer, the source code you will write will be subject to
>>> copyright matters and, if you want to contribute, you will have to give your
>>> agreement to this.
>>> This is only possible using your real name.
>>>
>>> I am inviting you to read: Documentation/process/submitting-patches.rst in
>>> this regard.
>>>
>>> Of course, as long as you do not submit source code, it does not really
>>> matter.  It may be more a question of "consistency".
>>>
>>> BR,
>>> Sebastien.
>>
>> I completely agree with you. If I decide to submit code and there is a
>> requirement, I will have to make a choice. BTW how would anyone verify
>> if I am really Joe Smith and I have not just created an email account
>> ?
>>
>> I just looked at the kernel that I am working with and it does not
>> have the file you pointed out to me. I read the first file and it does
>> not say anything about username neither did anyone objected when I
>> posted on netdev.
>>
>> ubuntu-server:~/linux/linux-stable-v4.9.9/Documentation$ find . -name
>> \*patches\* -print
>> ./hwmon/submitting-patches
>> ./applying-patches.txt
>> ./devicetree/bindings/submitting-patches.txt
>>
>>
>>
>>
>> --
>> CS1
>>
>> _______________________________________________
>> Kernelnewbies mailing list
>> Kernelnewbies at kernelnewbies.org
>> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
> https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux-stable.git/plain/Documentation/SubmittingPatches?id=refs/tags/v4.9.23
>
> 11) Sign your work
> ------------------
>
> To improve tracking of who did what, especially with patches that can
> percolate to their final resting place in the kernel through several
> layers of maintainers, we've introduced a "sign-off" procedure on
> patches that are being emailed around.
>
> The sign-off is a simple line at the end of the explanation for the
> patch, which certifies that you wrote it or otherwise have the right to
> pass it on as an open-source patch.  The rules are pretty simple: if you
> can certify the below:
>
> Developer's Certificate of Origin 1.1
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>
> By making a contribution to this project, I certify that:
>
>         (a) The contribution was created in whole or in part by me and I
>             have the right to submit it under the open source license
>             indicated in the file; or
>
>         (b) The contribution is based upon previous work that, to the best
>             of my knowledge, is covered under an appropriate open source
>             license and I have the right under that license to submit that
>             work with modifications, whether created in whole or in part
>             by me, under the same open source license (unless I am
>             permitted to submit under a different license), as indicated
>             in the file; or
>
>         (c) The contribution was provided directly to me by some other
>             person who certified (a), (b) or (c) and I have not modified
>             it.
>
>         (d) I understand and agree that this project and the contribution
>             are public and that a record of the contribution (including all
>             personal information I submit with it, including my sign-off) is
>             maintained indefinitely and may be redistributed consistent with
>             this project or the open source license(s) involved.
>
> then you just add a line saying::
>
> Signed-off-by: Random J Developer <random@developer.example.org>
>
> using your real name (sorry, no pseudonyms or anonymous contributions.)

How does anyone know what my real name is. I can just have an account
that says I am Random J Developer and my email is XXXX at gmail.com. Just
like the example.  I can even change the name that appears on the
email, I have just changed mine to Joe Smith.

Anyways let's not spend time on this and concentrate on the technical
stuff. If I submit code I will find out.



-- 
CS1

What is the fastest way to build and boot a kernel

[Bjørn Mork]

Joe Smith <codesoldier1@gmail.com> writes:
> On Thu, Apr 20, 2017 at 9:31 AM, Alexander Kapshuk
> <alexander.kapshuk@gmail.com> wrote:
>
>> then you just add a line saying::
>>
>> Signed-off-by: Random J Developer <random@developer.example.org>
>>
>> using your real name (sorry, no pseudonyms or anonymous contributions.)
>
> How does anyone know what my real name is.

No one does. It's up to you to make sure your name is real :)

An example of what might otherwise happen:
https://lwn.net/Articles/194729/



Bj?rn

What is the fastest way to build and boot a kernel

[Joe Smith]

On Thu, Apr 20, 2017 at 10:50 AM, Bj?rn Mork <bjorn@mork.no> wrote:
> Joe Smith <codesoldier1@gmail.com> writes:
>> On Thu, Apr 20, 2017 at 9:31 AM, Alexander Kapshuk
>> <alexander.kapshuk@gmail.com> wrote:
>>
>>> then you just add a line saying::
>>>
>>> Signed-off-by: Random J Developer <random@developer.example.org>
>>>
>>> using your real name (sorry, no pseudonyms or anonymous contributions.)
>>
>> How does anyone know what my real name is.
>
> No one does. It's up to you to make sure your name is real :)
>
> An example of what might otherwise happen:
> https://lwn.net/Articles/194729/
>
>
>
> Bj?rn

Excellent example but please note this

" For this reason, people contributing code which demonstrates *deep
knowledge of undocumented hardware* will often be asked just how they came
by that knowledge. Verifying the answer can be difficult, however. Our
defenses are thin, but it is hard to see how they could be improved without
killing the process entirely."

In cases where IP rights are an issue I can understand requiring someone to
reveal their true identity. Other than that I don't see any reason not to
accept an enhancement or bug fix to  Linux Kernel coming from an anonymous
source. If there is an IP issue, the submitter could reveal their identity
to a select group of people or not as the submitter did in this case. If we
need to really enforce this requirement then one would have to sign a legal
document -- Some software contributions do require that.


-- 
JS
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What is the fastest way to build and boot a kernel

[Bjørn Mork]

Joe Smith <codesoldier1@gmail.com> writes:

> In cases where IP rights are an issue

Very few maintainers are lawyers. They cannot make that assertion.

The administrative rules are simple, both for submitters and
maintainers. They have to be.


Bj?rn

What is the fastest way to build and boot a kernel

[Aruna Hewapathirane]

>> On Tue, Apr 18, 2017 at 11:59 AM, Code Soldier1 <codesoldier1@gmail.com>
wrote:
>> Hi,

>> Can someone suggest what is the fastest way to build a minimal kernel
>> and boot.

Two ways to build a minimal kernel. Try make localmodconfig or make
tinyconfig and see what fits your needs best. If this is still not what you
need then you have to tweak things using make menuconfig ( can be a real
pain in the butt... :)

>> For example if I am working on TCP and would like to make a
>> small change and reboot, what is the fastest way, I rather not build
>> the whole kernel.

Stay away from make menuconfig after the initial compile. The first time
you use make menuconfig it will create .config for you. As long as you do
not mess with the .config you can simply run make and should be able to
build just the file(s) you changed.

Keep in mind somethings are statically linked in to the kernel, meaning
'built-in' and if you touch those may trigger a full compile.

To get a faster compile/build use make parallel build with -j option. Where
-j is the number of processors available to you.
For eg: make -j4

Also compile for the target architecture only: make ARCH=<your
architecture> -jN

UML ( User mode linux ) I have found is faster for reasons yet to be
comprehended by me :)

Hope this helps and monikers are good, whats wrong with slap that code with
a flying trout eh ?

Aruna












> Thanks
>
> --
> CS1
>
> _______________________________________________
> Kernelnewbies mailing list
> Kernelnewbies at kernelnewbies.org
> https://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
>
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What is the fastest way to build and boot a kernel

[Stephen Brennan]

On Tue, Apr 18, 2017 at 08:59:36AM -0700, Code Soldier1 wrote:
> Can someone suggest what is the fastest way to build a minimal kernel
> and boot. For example if I am working on TCP and would like to make a
> small change and reboot, what is the fastest way, I rather not build
> the whole kernel.

To add to the already great list of advice (some of which I could have used
earlier in my life), I have found that virtual machines can be very useful. In
particular, there are tools [1] that allow you to run a linux kernel within a
virtual machine that shares your filesystem. You can use a quite minimal kernel
configuration, and the resulting build times are around 5 seconds for
incremental builds, and booting your new kernel in a virtual machine happens in
mere seconds.

Stephen

[1]: https://github.com/g2p/vido