[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Alexander Egorenkov]

Enables to build an uncompressed Linux kernel.

Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
---
 linux/Config.in | 3 +++
 linux/linux.mk  | 1 +
 2 files changed, 4 insertions(+)

diff --git a/linux/Config.in b/linux/Config.in
index 3370162faa..c09f70c4ac 100644
--- a/linux/Config.in
+++ b/linux/Config.in
@@ -329,6 +329,9 @@ config BR2_LINUX_KERNEL_XZ
 config BR2_LINUX_KERNEL_ZSTD
 	bool "zstd compression"
 
+config BR2_LINUX_KERNEL_UNCOMPRESSED
+	bool "uncompressed"
+
 endchoice
 
 config BR2_LINUX_KERNEL_IMAGE_TARGET_NAME
diff --git a/linux/linux.mk b/linux/linux.mk
index 5e4b319cf1..1457228eb9 100644
--- a/linux/linux.mk
+++ b/linux/linux.mk
@@ -111,6 +111,7 @@ LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZMA) += CONFIG_KERNEL_LZMA
 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZO) += CONFIG_KERNEL_LZO
 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_XZ) += CONFIG_KERNEL_XZ
 LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_ZSTD) += CONFIG_KERNEL_ZSTD
+LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_UNCOMPRESSED) += CONFIG_KERNEL_UNCOMPRESSED
 
 ifeq ($(BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL),y)
 LINUX_DEPENDENCIES += host-openssl
-- 
2.26.3

[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Peter Korsgaard]

>>>>> "Alexander" == Alexander Egorenkov <egorenar@linux.ibm.com> writes:

 > Enables to build an uncompressed Linux kernel.
 > Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
 > ---
 >  linux/Config.in | 3 +++
 >  linux/linux.mk  | 1 +
 >  2 files changed, 4 insertions(+)

 > diff --git a/linux/Config.in b/linux/Config.in
 > index 3370162faa..c09f70c4ac 100644
 > --- a/linux/Config.in
 > +++ b/linux/Config.in
 > @@ -329,6 +329,9 @@ config BR2_LINUX_KERNEL_XZ
 >  config BR2_LINUX_KERNEL_ZSTD
 >  	bool "zstd compression"
 
 > +config BR2_LINUX_KERNEL_UNCOMPRESSED
 > +	bool "uncompressed"

It looks like this is a s390-specific option:

commit 89b5202e81df9f0f0f0a11cf8c78bc8bfdc52a21
Author: Vasily Gorbik <gor@linux.ibm.com>
Date:   Wed Jun 13 00:00:25 2018 +0200

    s390/decompressor: support uncompressed kernel


So it should depend on BR2_s390x.

 > +
 >  endchoice
 
 >  config BR2_LINUX_KERNEL_IMAGE_TARGET_NAME
 > diff --git a/linux/linux.mk b/linux/linux.mk
 > index 5e4b319cf1..1457228eb9 100644
 > --- a/linux/linux.mk
 > +++ b/linux/linux.mk
 > @@ -111,6 +111,7 @@ LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZMA) += CONFIG_KERNEL_LZMA
 >  LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_LZO) += CONFIG_KERNEL_LZO
 >  LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_XZ) += CONFIG_KERNEL_XZ
 >  LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_ZSTD) += CONFIG_KERNEL_ZSTD
 > +LINUX_COMPRESSION_OPT_$(BR2_LINUX_KERNEL_UNCOMPRESSED) += CONFIG_KERNEL_UNCOMPRESSED
 
 >  ifeq ($(BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL),y)
 >  LINUX_DEPENDENCIES += host-openssl
 > -- 
 > 2.26.3

 > _______________________________________________
 > buildroot mailing list
 > buildroot at busybox.net
 > http://lists.busybox.net/mailman/listinfo/buildroot

-- 
Bye, Peter Korsgaard

[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Thomas Petazzoni]

On Wed, 24 Mar 2021 12:45:22 +0100
Alexander Egorenkov <egorenar@linux.ibm.com> wrote:

> Enables to build an uncompressed Linux kernel.
> 
> Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
> ---
>  linux/Config.in | 3 +++
>  linux/linux.mk  | 1 +
>  2 files changed, 4 insertions(+)

I have applied, after making the option conditional on BR2_s390x, as
suggested by Peter. Thanks!

Thomas
-- 
Thomas Petazzoni, CTO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Thomas Petazzoni]

On Fri, 26 Mar 2021 23:59:20 +0100
Peter Korsgaard <peter@korsgaard.com> wrote:

> It looks like this is a s390-specific option:
> 
> commit 89b5202e81df9f0f0f0a11cf8c78bc8bfdc52a21
> Author: Vasily Gorbik <gor@linux.ibm.com>
> Date:   Wed Jun 13 00:00:25 2018 +0200
> 
>     s390/decompressor: support uncompressed kernel
> 
> 
> So it should depend on BR2_s390x.

This is true... but in fact also applies to our other compression
options. For example, if you enable BR2_LINUX_KERNEL_LZMA on arm64, it
does nothing, because this is not supported on arm64.

Or if you use BR2_LINUX_KERNEL_ZSTD, it will only work on mips and x86,
none of the other CPU architectures support that.

And of course, since this is changing from one version of the kernel to
another, we can't really add such dependencies in Buildroot. I've done
so for the uncompressed/s390 case because it felt a bit "special", but
in the general case, it doesn't work :-/

The only way would be some kind of build-time verification that the
option was really taken into account, to at least abort the build if
the option doesn't do anything.

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering
https://bootlin.com

[Buildroot] [PATCH 1/1] linux: support uncompressed kernel

[Alexander Egorenkov]

Thomas Petazzoni <thomas.petazzoni@bootlin.com> writes:

> On Wed, 24 Mar 2021 12:45:22 +0100
> Alexander Egorenkov <egorenar@linux.ibm.com> wrote:
>
>> Enables to build an uncompressed Linux kernel.
>> 
>> Signed-off-by: Alexander Egorenkov <egorenar@linux.ibm.com>
>> ---
>>  linux/Config.in | 3 +++
>>  linux/linux.mk  | 1 +
>>  2 files changed, 4 insertions(+)
>
> I have applied, after making the option conditional on BR2_s390x, as
> suggested by Peter. Thanks!
>
> Thomas
> -- 
> Thomas Petazzoni, CTO, Bootlin
> Embedded Linux and Kernel engineering
> https://bootlin.com

Thank you very much

Regards
Alex