Re: [PATCH 2/2] kernel.bbclass: do_strip: allow recipes to strip the kernel

[Michel Thebeau <michel.thebeau@windriver.com>]

On 13-04-08 05:24 PM, michel.thebeau@windriver.com wrote:
> From: Michel Thebeau <michel.thebeau@windriver.com>
> 
> Allow recipes to specify sections to be stripped from the kernel output
> using KERNEL_IMAGE_STRIP.  For example:
> 
> KERNEL_IMAGE_STRIP = ".comment .unwanted"

s/KERNEL_IMAGE_STRIP/KERNEL_IMAGE_STRIP_EXTRA_SECTIONS

Throughout

> 
> The kernel output is stripped in place.

The subject was supposed to say "v2"


> 
> Since the toolchain does not give indication when the specified sections
> are absent, we read the sections first and make this report by issuing a
> warning to the developer.
> 
> The toolchain by default strips the image with the -s option (even
> when -s is not specified):
> -s --strip-all       Remove all symbol and relocation information
> 
> For example, these sections are always removed:
> .debug_aranges
> .debug_info
> .debug_abbrev
> .debug_line
> .debug_frame
> .debug_str
> .debug_loc
> .debug_ranges
> .symtab
> .strtab
> 
> In addition to these, the sections listed in KERNEL_IMAGE_STRIP will
> also be removed.
> 
> Only stripping of vmlinux (elf) is supported at this time.  A warning
> will be given if the image type is not vmlinux.
> 
> Stripping the image could also be done in the kernel, but that would
> only work for linux-yocto based kernels, so it's not the route we
> decided to go.
> 
> [YOCTO 3515]
> 
> Signed-off-by: Michel Thebeau <michel.thebeau@windriver.com>
> ---
>  meta/classes/kernel.bbclass |   30 ++++++++++++++++++++++++++++--
>  1 file changed, 28 insertions(+), 2 deletions(-)
> 
> diff --git a/meta/classes/kernel.bbclass b/meta/classes/kernel.bbclass
> index af58887..4c2c9b9 100644
> --- a/meta/classes/kernel.bbclass
> +++ b/meta/classes/kernel.bbclass
> @@ -88,7 +88,7 @@ do_compile_kernelmodules() {
>  		bbnote "no modules to compile"
>  	fi
>  }
> -addtask compile_kernelmodules after do_compile before do_install
> +addtask compile_kernelmodules after do_compile before do_strip
>  
>  kernel_do_install() {
>  	#
> @@ -289,6 +289,32 @@ python split_kernel_packages () {
>      do_split_packages(d, root='/lib/firmware', file_regex='^(.*)\.cis$', output_pattern='kernel-firmware-%s', description='Firmware for %s', recursive=True, extra_depends='')
>  }
>  
> +do_strip() {
> +	if [ -n "${KERNEL_IMAGE_STRIP}" ]; then
> +		if [[ "${KERNEL_IMAGETYPE}" != "vmlinux" ]]; then
> +			bbwarn "image type will not be stripped (not supported): ${KERNEL_IMAGETYPE}"
> +			return
> +		fi
> +
> +		cd ${B}
> +		headers=`"$CROSS_COMPILE"readelf -S ${KERNEL_OUTPUT} | \
> +			  grep "^ \{1,\}\[[0-9 ]\{1,\}\] [^ ]" | \
> +			  sed "s/^ \{1,\}\[[0-9 ]\{1,\}\] //" | \
> +			  gawk '{print $1}'`
> +
> +		for str in ${KERNEL_IMAGE_STRIP}; do {
> +			if [[ "$headers" != *"$str"* ]]; then
> +				bbwarn "Section not found: $str";
> +			fi
> +
> +			"$CROSS_COMPILE"strip -s -R $str ${KERNEL_OUTPUT}
> +		}; done

And I'll add a comment here

bbnote "KERNEL_IMAGE_STRIP_EXTRA_SECTIONS is set, stripping sections:" \
         "${KERNEL_IMAGE_STRIP_EXTRA_SECTIONS}"

Michel

> +	fi;
> +}
> +do_strip[dirs] = "${B}"
> +
> +addtask do_strip before do_sizecheck after do_kernel_link_vmlinux
> +
>  # Support checking the kernel size since some kernels need to reside in partitions
>  # with a fixed length or there is a limit in transferring the kernel to memory
>  do_sizecheck() {
> @@ -302,7 +328,7 @@ do_sizecheck() {
>  }
>  do_sizecheck[dirs] = "${B}"
>  
> -addtask sizecheck before do_install after do_kernel_link_vmlinux
> +addtask sizecheck before do_install after do_strip
>  
>  KERNEL_IMAGE_BASE_NAME ?= "${KERNEL_IMAGETYPE}-${PE}-${PV}-${PR}-${MACHINE}-${DATETIME}"
>  # Don't include the DATETIME variable in the sstate package signatures
>