diff mbox series

[v6] build: kni cross-compilation support

Message ID 1613048386-655-1-git-send-email-juraj.linkes@pantheon.tech (mailing list archive)
State Accepted
Delegated to: Thomas Monjalon
Headers show
Series [v6] build: kni cross-compilation support | expand

Checks

Context Check Description
ci/checkpatch success coding style OK
ci/iol-mellanox-Functional success Functional Testing PASS
ci/iol-testing warning Testing issues
ci/iol-mellanox-Performance success Performance Testing PASS
ci/intel-Testing success Testing PASS
ci/iol-intel-Performance success Performance Testing PASS
ci/iol-intel-Functional success Functional Testing PASS
ci/iol-broadcom-Functional success Functional Testing PASS
ci/iol-broadcom-Performance success Performance Testing PASS
ci/Intel-compilation success Compilation OK

Commit Message

Juraj Linkeš Feb. 11, 2021, 12:59 p.m. UTC
The kni linux module is using a custom target for building, which
doesn't take into account any cross compilation arguments. The arguments
in question are ARCH, CROSS_COMPILE (for gcc, clang) and CC, LD (for
clang). Get those from the cross file and pass them to the custom
target.

The user supplied path may not contain the 'build' directory, such as
when using cross-compiled headers, so only append that in the default
case (when no path is supplied in native builds) and use the unmodified
path from the user otherwise. Also modify the install path accordingly.

Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>
---
 kernel/linux/kni/meson.build |  8 ++--
 kernel/linux/meson.build     | 90 ++++++++++++++++++++++++++++++------
 meson_options.txt            |  2 +-
 3 files changed, 82 insertions(+), 18 deletions(-)

Comments

Juraj Linkeš March 9, 2021, 8:47 a.m. UTC | #1
Hi Folks,

Does anyone have any comments? Is the patch ready? If so, please send acks or reviewed-by, thanks.

Andrew, did you get a chance to test the patch?

Juraj

> -----Original Message-----
> From: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Sent: Thursday, February 11, 2021 2:00 PM
> To: bruce.richardson@intel.com; thomas@monjalon.net;
> Ruifeng.Wang@arm.com; Honnappa.Nagarahalli@arm.com;
> jerinjacobk@gmail.com; hemant.agrawal@nxp.com; ferruh.yigit@intel.com;
> aboyer@pensando.io
> Cc: dev@dpdk.org; Juraj Linkeš <juraj.linkes@pantheon.tech>
> Subject: [PATCH v6] build: kni cross-compilation support
> 
> The kni linux module is using a custom target for building, which doesn't take
> into account any cross compilation arguments. The arguments in question are
> ARCH, CROSS_COMPILE (for gcc, clang) and CC, LD (for clang). Get those from
> the cross file and pass them to the custom target.
> 
> The user supplied path may not contain the 'build' directory, such as when using
> cross-compiled headers, so only append that in the default case (when no path is
> supplied in native builds) and use the unmodified path from the user otherwise.
> Also modify the install path accordingly.
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>
> ---
>  kernel/linux/kni/meson.build |  8 ++--
>  kernel/linux/meson.build     | 90 ++++++++++++++++++++++++++++++------
>  meson_options.txt            |  2 +-
>  3 files changed, 82 insertions(+), 18 deletions(-)
> 
> diff --git a/kernel/linux/kni/meson.build b/kernel/linux/kni/meson.build index
> 07e0c9dae7..46b71c7418 100644
> --- a/kernel/linux/kni/meson.build
> +++ b/kernel/linux/kni/meson.build
> @@ -13,7 +13,7 @@ kni_sources = files(
>  custom_target('rte_kni',
>  	input: kni_sources,
>  	output: 'rte_kni.ko',
> -	command: ['make', '-j4', '-C', kernel_dir + '/build',
> +	command: ['make', '-j4', '-C', kernel_build_dir,
>  		'M=' + meson.current_build_dir(),
>  		'src=' + meson.current_source_dir(),
>  		'MODULE_CFLAGS=-include ' + meson.source_root() +
> '/config/rte_config.h' + @@ -21,8 +21,8 @@ custom_target('rte_kni',
>  		' -I' + meson.source_root() + '/lib/librte_kni' +
>  		' -I' + meson.build_root() +
>  		' -I' + meson.current_source_dir(),
> -		'modules'],
> +		'modules'] + cross_args,
>  	depends: kni_mkfile,
> -	install: true,
> -	install_dir: kernel_dir + '/extra/dpdk',
> +	install: install,
> +	install_dir: kernel_install_dir,
>  	build_by_default: get_option('enable_kmods')) diff --git
> a/kernel/linux/meson.build b/kernel/linux/meson.build index
> 5c864a4653..7b15e0fd44 100644
> --- a/kernel/linux/meson.build
> +++ b/kernel/linux/meson.build
> @@ -3,25 +3,89 @@
> 
>  subdirs = ['kni']
> 
> -# if we are cross-compiling we need kernel_dir specified -if
> get_option('kernel_dir') == '' and meson.is_cross_build()
> -	error('Need "kernel_dir" option for kmod compilation when cross-
> compiling')
> -endif
> +kernel_build_dir = get_option('kernel_dir') kernel_install_dir = ''
> +install = not meson.is_cross_build()
> +cross_args = []
> 
> -kernel_dir = get_option('kernel_dir')
> -if kernel_dir == ''
> -	# use default path for native builds
> +if not meson.is_cross_build()
> +	# native build
>  	kernel_version = run_command('uname', '-r').stdout().strip()
> -	kernel_dir = '/lib/modules/' + kernel_version
> +	kernel_install_dir = '/lib/modules/' + kernel_version + '/extra/dpdk'
> +	if kernel_build_dir == ''
> +		# use default path for native builds
> +		kernel_build_dir = '/lib/modules/' + kernel_version + '/build'
> +	endif
> +
> +	# test running make in kernel directory, using "make kernelversion"
> +	make_returncode = run_command('make', '-sC', kernel_build_dir,
> +			'kernelversion').returncode()
> +	if make_returncode != 0
> +		# backwards compatibility:
> +		# the headers could still be in the 'build' subdir
> +		if not kernel_build_dir.endswith('build') and not
> kernel_build_dir.endswith('build/')
> +			kernel_build_dir = join_paths(kernel_build_dir, 'build')
> +			make_returncode = run_command('make', '-sC',
> kernel_build_dir,
> +					'kernelversion').returncode()
> +		endif
> +	endif
> +
> +	if make_returncode != 0
> +		error('Cannot compile kernel modules as requested - are kernel
> headers installed?')
> +	endif
> +
> +	# DO ACTUAL MODULE BUILDING
> +	foreach d:subdirs
> +		subdir(d)
> +	endforeach
> +
> +	subdir_done()
>  endif
> 
> -# test running make in kernel directory, using "make kernelversion"
> -make_returncode = run_command('make', '-sC', kernel_dir + '/build',
> -		'kernelversion').returncode()
> -if make_returncode != 0
> -	error('Cannot compile kernel modules as requested - are kernel headers
> installed?')
> +# cross build
> +# if we are cross-compiling we need kernel_build_dir specified if
> +kernel_build_dir == ''
> +	error('Need "kernel_dir" option for kmod compilation when
> +cross-compiling') endif cross_compiler = find_program('c').path() if
> +cross_compiler.endswith('gcc')
> +	cross_prefix = run_command([py3, '-c', 'print("' + cross_compiler +
> +'"[:-3])']).stdout().strip() elif cross_compiler.endswith('clang')
> +	cross_prefix = ''
> +	found_target = false
> +	# search for '-target' and use the arg that follows
> +	# (i.e. the value of '-target') as cross_prefix
> +	foreach cross_c_arg : meson.get_cross_property('c_args')
> +		if found_target and cross_prefix == ''
> +			cross_prefix = cross_c_arg
> +		endif
> +		if cross_c_arg == '-target'
> +			found_target = true
> +		endif
> +	endforeach
> +	if cross_prefix == ''
> +		error('Didn\'t find -target and its value in' +
> +		      ' c_args in input cross-file.')
> +	endif
> +	linker = 'lld'
> +	foreach cross_c_link_arg : meson.get_cross_property('c_link_args')
> +		if cross_c_link_arg.startswith('-fuse-ld')
> +			linker = cross_c_link_arg.split('=')[1]
> +		endif
> +	endforeach
> +	cross_args += ['CC=@0@'.format(cross_compiler),
> +'LD=ld.@0@'.format(linker)] else
> +	error('Unsupported cross compiler: @0@'.format(cross_compiler))
>  endif
> 
> +cross_arch = host_machine.cpu_family()
> +if host_machine.cpu_family() == 'aarch64'
> +	cross_arch = 'arm64'
> +endif
> +
> +cross_args += ['ARCH=@0@'.format(cross_arch),
> +	'CROSS_COMPILE=@0@'.format(cross_prefix)]
> +
>  # DO ACTUAL MODULE BUILDING
>  foreach d:subdirs
>  	subdir(d)
> diff --git a/meson_options.txt b/meson_options.txt index
> 6eff62e47d..3b8c5d316d 100644
> --- a/meson_options.txt
> +++ b/meson_options.txt
> @@ -19,7 +19,7 @@ option('ibverbs_link', type: 'combo', choices : ['static',
> 'shared', 'dlopen'],  option('include_subdir_arch', type: 'string', value: '',
>  	description: 'subdirectory where to install arch-dependent headers')
> option('kernel_dir', type: 'string', value: '',
> -	description: 'Path to the kernel for building kernel modules. Headers
> must be in $kernel_dir/build. Modules will be installed in
> $DEST_DIR/$kernel_dir/extra/dpdk.')
> +	description: 'Path to the kernel for building kernel modules. Headers
> +must be in $kernel_dir or $kernel_dir/build. Modules will be installed
> +in /lib/modules.')
>  option('machine', type: 'string', value: 'native',
>  	description: 'set the target machine type')  option('max_ethports', type:
> 'integer', value: 32,
> --
> 2.20.1
Andrew Boyer March 9, 2021, 4:26 p.m. UTC | #2
No, I am sorry, I have not tested it. I was able to remove rte_kni from our requirements so this is no longer a blocker for us.

-Andrew

> On Mar 9, 2021, at 3:47 AM, Juraj Linkeš <juraj.linkes@pantheon.tech> wrote:
> 
> Hi Folks,
> 
> Does anyone have any comments? Is the patch ready? If so, please send acks or reviewed-by, thanks.
> 
> Andrew, did you get a chance to test the patch?
> 
> Juraj
> 
>> -----Original Message-----
>> From: Juraj Linkeš <juraj.linkes@pantheon.tech>
>> Sent: Thursday, February 11, 2021 2:00 PM
>> To: bruce.richardson@intel.com; thomas@monjalon.net;
>> Ruifeng.Wang@arm.com; Honnappa.Nagarahalli@arm.com;
>> jerinjacobk@gmail.com; hemant.agrawal@nxp.com; ferruh.yigit@intel.com;
>> aboyer@pensando.io
>> Cc: dev@dpdk.org; Juraj Linkeš <juraj.linkes@pantheon.tech>
>> Subject: [PATCH v6] build: kni cross-compilation support
>> 
>> The kni linux module is using a custom target for building, which doesn't take
>> into account any cross compilation arguments. The arguments in question are
>> ARCH, CROSS_COMPILE (for gcc, clang) and CC, LD (for clang). Get those from
>> the cross file and pass them to the custom target.
>> 
>> The user supplied path may not contain the 'build' directory, such as when using
>> cross-compiled headers, so only append that in the default case (when no path is
>> supplied in native builds) and use the unmodified path from the user otherwise.
>> Also modify the install path accordingly.
>> 
>> Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
>> Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>
>> ---
>> kernel/linux/kni/meson.build |  8 ++--
>> kernel/linux/meson.build     | 90 ++++++++++++++++++++++++++++++------
>> meson_options.txt            |  2 +-
>> 3 files changed, 82 insertions(+), 18 deletions(-)
>> 
>> diff --git a/kernel/linux/kni/meson.build b/kernel/linux/kni/meson.build index
>> 07e0c9dae7..46b71c7418 100644
>> --- a/kernel/linux/kni/meson.build
>> +++ b/kernel/linux/kni/meson.build
>> @@ -13,7 +13,7 @@ kni_sources = files(
>> custom_target('rte_kni',
>> 	input: kni_sources,
>> 	output: 'rte_kni.ko',
>> -	command: ['make', '-j4', '-C', kernel_dir + '/build',
>> +	command: ['make', '-j4', '-C', kernel_build_dir,
>> 		'M=' + meson.current_build_dir(),
>> 		'src=' + meson.current_source_dir(),
>> 		'MODULE_CFLAGS=-include ' + meson.source_root() +
>> '/config/rte_config.h' + @@ -21,8 +21,8 @@ custom_target('rte_kni',
>> 		' -I' + meson.source_root() + '/lib/librte_kni' +
>> 		' -I' + meson.build_root() +
>> 		' -I' + meson.current_source_dir(),
>> -		'modules'],
>> +		'modules'] + cross_args,
>> 	depends: kni_mkfile,
>> -	install: true,
>> -	install_dir: kernel_dir + '/extra/dpdk',
>> +	install: install,
>> +	install_dir: kernel_install_dir,
>> 	build_by_default: get_option('enable_kmods')) diff --git
>> a/kernel/linux/meson.build b/kernel/linux/meson.build index
>> 5c864a4653..7b15e0fd44 100644
>> --- a/kernel/linux/meson.build
>> +++ b/kernel/linux/meson.build
>> @@ -3,25 +3,89 @@
>> 
>> subdirs = ['kni']
>> 
>> -# if we are cross-compiling we need kernel_dir specified -if
>> get_option('kernel_dir') == '' and meson.is_cross_build()
>> -	error('Need "kernel_dir" option for kmod compilation when cross-
>> compiling')
>> -endif
>> +kernel_build_dir = get_option('kernel_dir') kernel_install_dir = ''
>> +install = not meson.is_cross_build()
>> +cross_args = []
>> 
>> -kernel_dir = get_option('kernel_dir')
>> -if kernel_dir == ''
>> -	# use default path for native builds
>> +if not meson.is_cross_build()
>> +	# native build
>> 	kernel_version = run_command('uname', '-r').stdout().strip()
>> -	kernel_dir = '/lib/modules/' + kernel_version
>> +	kernel_install_dir = '/lib/modules/' + kernel_version + '/extra/dpdk'
>> +	if kernel_build_dir == ''
>> +		# use default path for native builds
>> +		kernel_build_dir = '/lib/modules/' + kernel_version + '/build'
>> +	endif
>> +
>> +	# test running make in kernel directory, using "make kernelversion"
>> +	make_returncode = run_command('make', '-sC', kernel_build_dir,
>> +			'kernelversion').returncode()
>> +	if make_returncode != 0
>> +		# backwards compatibility:
>> +		# the headers could still be in the 'build' subdir
>> +		if not kernel_build_dir.endswith('build') and not
>> kernel_build_dir.endswith('build/')
>> +			kernel_build_dir = join_paths(kernel_build_dir, 'build')
>> +			make_returncode = run_command('make', '-sC',
>> kernel_build_dir,
>> +					'kernelversion').returncode()
>> +		endif
>> +	endif
>> +
>> +	if make_returncode != 0
>> +		error('Cannot compile kernel modules as requested - are kernel
>> headers installed?')
>> +	endif
>> +
>> +	# DO ACTUAL MODULE BUILDING
>> +	foreach d:subdirs
>> +		subdir(d)
>> +	endforeach
>> +
>> +	subdir_done()
>> endif
>> 
>> -# test running make in kernel directory, using "make kernelversion"
>> -make_returncode = run_command('make', '-sC', kernel_dir + '/build',
>> -		'kernelversion').returncode()
>> -if make_returncode != 0
>> -	error('Cannot compile kernel modules as requested - are kernel headers
>> installed?')
>> +# cross build
>> +# if we are cross-compiling we need kernel_build_dir specified if
>> +kernel_build_dir == ''
>> +	error('Need "kernel_dir" option for kmod compilation when
>> +cross-compiling') endif cross_compiler = find_program('c').path() if
>> +cross_compiler.endswith('gcc')
>> +	cross_prefix = run_command([py3, '-c', 'print("' + cross_compiler +
>> +'"[:-3])']).stdout().strip() elif cross_compiler.endswith('clang')
>> +	cross_prefix = ''
>> +	found_target = false
>> +	# search for '-target' and use the arg that follows
>> +	# (i.e. the value of '-target') as cross_prefix
>> +	foreach cross_c_arg : meson.get_cross_property('c_args')
>> +		if found_target and cross_prefix == ''
>> +			cross_prefix = cross_c_arg
>> +		endif
>> +		if cross_c_arg == '-target'
>> +			found_target = true
>> +		endif
>> +	endforeach
>> +	if cross_prefix == ''
>> +		error('Didn\'t find -target and its value in' +
>> +		      ' c_args in input cross-file.')
>> +	endif
>> +	linker = 'lld'
>> +	foreach cross_c_link_arg : meson.get_cross_property('c_link_args')
>> +		if cross_c_link_arg.startswith('-fuse-ld')
>> +			linker = cross_c_link_arg.split('=')[1]
>> +		endif
>> +	endforeach
>> +	cross_args += ['CC=@0@'.format(cross_compiler),
>> +'LD=ld.@0@'.format(linker)] else
>> +	error('Unsupported cross compiler: @0@'.format(cross_compiler))
>> endif
>> 
>> +cross_arch = host_machine.cpu_family()
>> +if host_machine.cpu_family() == 'aarch64'
>> +	cross_arch = 'arm64'
>> +endif
>> +
>> +cross_args += ['ARCH=@0@'.format(cross_arch),
>> +	'CROSS_COMPILE=@0@'.format(cross_prefix)]
>> +
>> # DO ACTUAL MODULE BUILDING
>> foreach d:subdirs
>> 	subdir(d)
>> diff --git a/meson_options.txt b/meson_options.txt index
>> 6eff62e47d..3b8c5d316d 100644
>> --- a/meson_options.txt
>> +++ b/meson_options.txt
>> @@ -19,7 +19,7 @@ option('ibverbs_link', type: 'combo', choices : ['static',
>> 'shared', 'dlopen'],  option('include_subdir_arch', type: 'string', value: '',
>> 	description: 'subdirectory where to install arch-dependent headers')
>> option('kernel_dir', type: 'string', value: '',
>> -	description: 'Path to the kernel for building kernel modules. Headers
>> must be in $kernel_dir/build. Modules will be installed in
>> $DEST_DIR/$kernel_dir/extra/dpdk.')
>> +	description: 'Path to the kernel for building kernel modules. Headers
>> +must be in $kernel_dir or $kernel_dir/build. Modules will be installed
>> +in /lib/modules.')
>> option('machine', type: 'string', value: 'native',
>> 	description: 'set the target machine type')  option('max_ethports', type:
>> 'integer', value: 32,
>> --
>> 2.20.1
>
Thomas Monjalon March 15, 2021, 10:45 p.m. UTC | #3
11/02/2021 13:59, Juraj Linkeš:
> The kni linux module is using a custom target for building, which
> doesn't take into account any cross compilation arguments. The arguments
> in question are ARCH, CROSS_COMPILE (for gcc, clang) and CC, LD (for
> clang). Get those from the cross file and pass them to the custom
> target.
> 
> The user supplied path may not contain the 'build' directory, such as
> when using cross-compiled headers, so only append that in the default
> case (when no path is supplied in native builds) and use the unmodified
> path from the user otherwise. Also modify the install path accordingly.
> 
> Signed-off-by: Juraj Linkeš <juraj.linkes@pantheon.tech>
> Reviewed-by: Bruce Richardson <bruce.richardson@intel.com>

Applied, thanks
diff mbox series

Patch

diff --git a/kernel/linux/kni/meson.build b/kernel/linux/kni/meson.build
index 07e0c9dae7..46b71c7418 100644
--- a/kernel/linux/kni/meson.build
+++ b/kernel/linux/kni/meson.build
@@ -13,7 +13,7 @@  kni_sources = files(
 custom_target('rte_kni',
 	input: kni_sources,
 	output: 'rte_kni.ko',
-	command: ['make', '-j4', '-C', kernel_dir + '/build',
+	command: ['make', '-j4', '-C', kernel_build_dir,
 		'M=' + meson.current_build_dir(),
 		'src=' + meson.current_source_dir(),
 		'MODULE_CFLAGS=-include ' + meson.source_root() + '/config/rte_config.h' +
@@ -21,8 +21,8 @@  custom_target('rte_kni',
 		' -I' + meson.source_root() + '/lib/librte_kni' +
 		' -I' + meson.build_root() +
 		' -I' + meson.current_source_dir(),
-		'modules'],
+		'modules'] + cross_args,
 	depends: kni_mkfile,
-	install: true,
-	install_dir: kernel_dir + '/extra/dpdk',
+	install: install,
+	install_dir: kernel_install_dir,
 	build_by_default: get_option('enable_kmods'))
diff --git a/kernel/linux/meson.build b/kernel/linux/meson.build
index 5c864a4653..7b15e0fd44 100644
--- a/kernel/linux/meson.build
+++ b/kernel/linux/meson.build
@@ -3,25 +3,89 @@ 
 
 subdirs = ['kni']
 
-# if we are cross-compiling we need kernel_dir specified
-if get_option('kernel_dir') == '' and meson.is_cross_build()
-	error('Need "kernel_dir" option for kmod compilation when cross-compiling')
-endif
+kernel_build_dir = get_option('kernel_dir')
+kernel_install_dir = ''
+install = not meson.is_cross_build()
+cross_args = []
 
-kernel_dir = get_option('kernel_dir')
-if kernel_dir == ''
-	# use default path for native builds
+if not meson.is_cross_build()
+	# native build
 	kernel_version = run_command('uname', '-r').stdout().strip()
-	kernel_dir = '/lib/modules/' + kernel_version
+	kernel_install_dir = '/lib/modules/' + kernel_version + '/extra/dpdk'
+	if kernel_build_dir == ''
+		# use default path for native builds
+		kernel_build_dir = '/lib/modules/' + kernel_version + '/build'
+	endif
+
+	# test running make in kernel directory, using "make kernelversion"
+	make_returncode = run_command('make', '-sC', kernel_build_dir,
+			'kernelversion').returncode()
+	if make_returncode != 0
+		# backwards compatibility:
+		# the headers could still be in the 'build' subdir
+		if not kernel_build_dir.endswith('build') and not kernel_build_dir.endswith('build/')
+			kernel_build_dir = join_paths(kernel_build_dir, 'build')
+			make_returncode = run_command('make', '-sC', kernel_build_dir,
+					'kernelversion').returncode()
+		endif
+	endif
+
+	if make_returncode != 0
+		error('Cannot compile kernel modules as requested - are kernel headers installed?')
+	endif
+
+	# DO ACTUAL MODULE BUILDING
+	foreach d:subdirs
+		subdir(d)
+	endforeach
+
+	subdir_done()
 endif
 
-# test running make in kernel directory, using "make kernelversion"
-make_returncode = run_command('make', '-sC', kernel_dir + '/build',
-		'kernelversion').returncode()
-if make_returncode != 0
-	error('Cannot compile kernel modules as requested - are kernel headers installed?')
+# cross build
+# if we are cross-compiling we need kernel_build_dir specified
+if kernel_build_dir == ''
+	error('Need "kernel_dir" option for kmod compilation when cross-compiling')
+endif
+cross_compiler = find_program('c').path()
+if cross_compiler.endswith('gcc')
+	cross_prefix = run_command([py3, '-c', 'print("' + cross_compiler + '"[:-3])']).stdout().strip()
+elif cross_compiler.endswith('clang')
+	cross_prefix = ''
+	found_target = false
+	# search for '-target' and use the arg that follows
+	# (i.e. the value of '-target') as cross_prefix
+	foreach cross_c_arg : meson.get_cross_property('c_args')
+		if found_target and cross_prefix == ''
+			cross_prefix = cross_c_arg
+		endif
+		if cross_c_arg == '-target'
+			found_target = true
+		endif
+	endforeach
+	if cross_prefix == ''
+		error('Didn\'t find -target and its value in' +
+		      ' c_args in input cross-file.')
+	endif
+	linker = 'lld'
+	foreach cross_c_link_arg : meson.get_cross_property('c_link_args')
+		if cross_c_link_arg.startswith('-fuse-ld')
+			linker = cross_c_link_arg.split('=')[1]
+		endif
+	endforeach
+	cross_args += ['CC=@0@'.format(cross_compiler), 'LD=ld.@0@'.format(linker)]
+else
+	error('Unsupported cross compiler: @0@'.format(cross_compiler))
 endif
 
+cross_arch = host_machine.cpu_family()
+if host_machine.cpu_family() == 'aarch64'
+	cross_arch = 'arm64'
+endif
+
+cross_args += ['ARCH=@0@'.format(cross_arch),
+	'CROSS_COMPILE=@0@'.format(cross_prefix)]
+
 # DO ACTUAL MODULE BUILDING
 foreach d:subdirs
 	subdir(d)
diff --git a/meson_options.txt b/meson_options.txt
index 6eff62e47d..3b8c5d316d 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -19,7 +19,7 @@  option('ibverbs_link', type: 'combo', choices : ['static', 'shared', 'dlopen'],
 option('include_subdir_arch', type: 'string', value: '',
 	description: 'subdirectory where to install arch-dependent headers')
 option('kernel_dir', type: 'string', value: '',
-	description: 'Path to the kernel for building kernel modules. Headers must be in $kernel_dir/build. Modules will be installed in $DEST_DIR/$kernel_dir/extra/dpdk.')
+	description: 'Path to the kernel for building kernel modules. Headers must be in $kernel_dir or $kernel_dir/build. Modules will be installed in /lib/modules.')
 option('machine', type: 'string', value: 'native',
 	description: 'set the target machine type')
 option('max_ethports', type: 'integer', value: 32,