* [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image
@ 2023-09-17 15:21 Thomas Weißschuh
2023-09-18 16:20 ` Willy Tarreau
2023-09-19 11:47 ` Nicolas Schier
0 siblings, 2 replies; 3+ messages in thread
From: Thomas Weißschuh @ 2023-09-17 15:21 UTC (permalink / raw)
To: Masahiro Yamada, Nathan Chancellor, Nick Desaulniers,
Nicolas Schier, Willy Tarreau, Shuah Khan
Cc: linux-kbuild, linux-kernel, linux-kselftest,
Thomas Weißschuh
When the initramfs is embedded into the kernel each rebuild of it will
trigger a full kernel relink and all the expensive postprocessing steps.
Currently nolibc-test and therefore the initramfs are always rebuild,
even without source changes, leading to lots of slow kernel relinks.
Instead of linking the initramfs into the kernel assemble it manually
and pass it explicitly to qemu.
This avoids all of the kernel relinks.
Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
---
Currently the nolibc testsuite embeds the test executable into a kernel
image with CONFIG_INITRAMFS_SOURCE.
This forces a full kernel relink everytime the test executable is
updated.
This relinking step dominates the test cycle.
It is slower than building and running the test in qemu together.
With a bit of Makefile-shuffling the relinking can be avoided.
---
Changes in v2:
- avoid need to modify top-level Makefile
- drop patch removing "rerun" target
- add kernel-standalone target
- Link to v1: https://lore.kernel.org/r/20230916-nolibc-initramfs-v1-0-4416ecedca6d@weissschuh.net
---
tools/testing/selftests/nolibc/Makefile | 42 ++++++++++++++++++++-------------
1 file changed, 26 insertions(+), 16 deletions(-)
diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
index 689658f81a19..ee6a9ad28cfd 100644
--- a/tools/testing/selftests/nolibc/Makefile
+++ b/tools/testing/selftests/nolibc/Makefile
@@ -131,18 +131,20 @@ REPORT ?= awk '/\[OK\][\r]*$$/{p++} /\[FAIL\][\r]*$$/{if (!f) printf("\n"); f++
help:
@echo "Supported targets under selftests/nolibc:"
- @echo " all call the \"run\" target below"
- @echo " help this help"
- @echo " sysroot create the nolibc sysroot here (uses \$$ARCH)"
- @echo " nolibc-test build the executable (uses \$$CC and \$$CROSS_COMPILE)"
- @echo " libc-test build an executable using the compiler's default libc instead"
- @echo " run-user runs the executable under QEMU (uses \$$XARCH, \$$TEST)"
- @echo " initramfs prepare the initramfs with nolibc-test"
- @echo " defconfig create a fresh new default config (uses \$$XARCH)"
- @echo " kernel (re)build the kernel with the initramfs (uses \$$XARCH)"
- @echo " run runs the kernel in QEMU after building it (uses \$$XARCH, \$$TEST)"
- @echo " rerun runs a previously prebuilt kernel in QEMU (uses \$$XARCH, \$$TEST)"
- @echo " clean clean the sysroot, initramfs, build and output files"
+ @echo " all call the \"run\" target below"
+ @echo " help this help"
+ @echo " sysroot create the nolibc sysroot here (uses \$$ARCH)"
+ @echo " nolibc-test build the executable (uses \$$CC and \$$CROSS_COMPILE)"
+ @echo " libc-test build an executable using the compiler's default libc instead"
+ @echo " run-user runs the executable under QEMU (uses \$$XARCH, \$$TEST)"
+ @echo " initramfs.cpio prepare the initramfs archive with nolibc-test"
+ @echo " initramfs prepare the initramfs tree with nolibc-test"
+ @echo " defconfig create a fresh new default config (uses \$$XARCH)"
+ @echo " kernel (re)build the kernel (uses \$$XARCH)"
+ @echo " kernel-standalone (re)build the kernel with the initramfs (uses \$$XARCH)"
+ @echo " run runs the kernel in QEMU after building it (uses \$$XARCH, \$$TEST)"
+ @echo " rerun runs a previously prebuilt kernel in QEMU (uses \$$XARCH, \$$TEST)"
+ @echo " clean clean the sysroot, initramfs, build and output files"
@echo ""
@echo "The output file is \"run.out\". Test ranges may be passed using \$$TEST."
@echo ""
@@ -195,6 +197,9 @@ run-user: nolibc-test
$(Q)qemu-$(QEMU_ARCH) ./nolibc-test > "$(CURDIR)/run.out" || :
$(Q)$(REPORT) $(CURDIR)/run.out
+initramfs.cpio: kernel nolibc-test
+ $(QUIET_GEN)echo 'file /init nolibc-test 755 0 0' | $(srctree)/usr/gen_init_cpio - > initramfs.cpio
+
initramfs: nolibc-test
$(QUIET_MKDIR)mkdir -p initramfs
$(call QUIET_INSTALL, initramfs/init)
@@ -203,17 +208,20 @@ initramfs: nolibc-test
defconfig:
$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) mrproper $(DEFCONFIG) prepare
-kernel: initramfs
+kernel:
+ $(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME)
+
+kernel-standalone: initramfs
$(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME) CONFIG_INITRAMFS_SOURCE=$(CURDIR)/initramfs
# run the tests after building the kernel
-run: kernel
- $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
+run: kernel initramfs.cpio
+ $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -initrd initramfs.cpio -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
$(Q)$(REPORT) $(CURDIR)/run.out
# re-run the tests from an existing kernel
rerun:
- $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
+ $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -initrd initramfs.cpio -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
$(Q)$(REPORT) $(CURDIR)/run.out
# report with existing test log
@@ -227,6 +235,8 @@ clean:
$(Q)rm -f nolibc-test
$(call QUIET_CLEAN, libc-test)
$(Q)rm -f libc-test
+ $(call QUIET_CLEAN, initramfs.cpio)
+ $(Q)rm -rf initramfs.cpio
$(call QUIET_CLEAN, initramfs)
$(Q)rm -rf initramfs
$(call QUIET_CLEAN, run.out)
---
base-commit: 3f79a57865b33f49fdae6655510bd27c8e6610e0
change-id: 20230916-nolibc-initramfs-4fd00eac3256
Best regards,
--
Thomas Weißschuh <linux@weissschuh.net>
^ permalink raw reply related [flat|nested] 3+ messages in thread* Re: [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image
2023-09-17 15:21 [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image Thomas Weißschuh
@ 2023-09-18 16:20 ` Willy Tarreau
2023-09-19 11:47 ` Nicolas Schier
1 sibling, 0 replies; 3+ messages in thread
From: Willy Tarreau @ 2023-09-18 16:20 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Masahiro Yamada, Nathan Chancellor, Nick Desaulniers,
Nicolas Schier, Shuah Khan, linux-kbuild, linux-kernel,
linux-kselftest
Hi Thomas,
On Sun, Sep 17, 2023 at 05:21:38PM +0200, Thomas Weißschuh wrote:
> When the initramfs is embedded into the kernel each rebuild of it will
> trigger a full kernel relink and all the expensive postprocessing steps.
>
> Currently nolibc-test and therefore the initramfs are always rebuild,
> even without source changes, leading to lots of slow kernel relinks.
>
> Instead of linking the initramfs into the kernel assemble it manually
> and pass it explicitly to qemu.
> This avoids all of the kernel relinks.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
OK, let's try it!
thanks,
Willy
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image
2023-09-17 15:21 [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image Thomas Weißschuh
2023-09-18 16:20 ` Willy Tarreau
@ 2023-09-19 11:47 ` Nicolas Schier
1 sibling, 0 replies; 3+ messages in thread
From: Nicolas Schier @ 2023-09-19 11:47 UTC (permalink / raw)
To: Thomas Weißschuh
Cc: Masahiro Yamada, Nathan Chancellor, Nick Desaulniers,
Willy Tarreau, Shuah Khan, linux-kbuild, linux-kernel,
linux-kselftest
On Sun, Sep 17, 2023 at 05:21:38PM +0200 Thomas Weißschuh wrote:
> When the initramfs is embedded into the kernel each rebuild of it will
> trigger a full kernel relink and all the expensive postprocessing steps.
>
> Currently nolibc-test and therefore the initramfs are always rebuild,
> even without source changes, leading to lots of slow kernel relinks.
>
> Instead of linking the initramfs into the kernel assemble it manually
> and pass it explicitly to qemu.
> This avoids all of the kernel relinks.
>
> Signed-off-by: Thomas Weißschuh <linux@weissschuh.net>
> ---
> Currently the nolibc testsuite embeds the test executable into a kernel
> image with CONFIG_INITRAMFS_SOURCE.
> This forces a full kernel relink everytime the test executable is
> updated.
>
> This relinking step dominates the test cycle.
> It is slower than building and running the test in qemu together.
>
> With a bit of Makefile-shuffling the relinking can be avoided.
> ---
> Changes in v2:
> - avoid need to modify top-level Makefile
> - drop patch removing "rerun" target
> - add kernel-standalone target
> - Link to v1: https://lore.kernel.org/r/20230916-nolibc-initramfs-v1-0-4416ecedca6d@weissschuh.net
> ---
Thanks, seems to work as described (and I am surprised how fast the 'run'
target is) and patch looks good to me.
Reviewed-by: Nicolas Schier <nicolas@fjasle.eu>
> tools/testing/selftests/nolibc/Makefile | 42 ++++++++++++++++++++-------------
> 1 file changed, 26 insertions(+), 16 deletions(-)
>
> diff --git a/tools/testing/selftests/nolibc/Makefile b/tools/testing/selftests/nolibc/Makefile
> index 689658f81a19..ee6a9ad28cfd 100644
> --- a/tools/testing/selftests/nolibc/Makefile
> +++ b/tools/testing/selftests/nolibc/Makefile
> @@ -131,18 +131,20 @@ REPORT ?= awk '/\[OK\][\r]*$$/{p++} /\[FAIL\][\r]*$$/{if (!f) printf("\n"); f++
>
> help:
> @echo "Supported targets under selftests/nolibc:"
> - @echo " all call the \"run\" target below"
> - @echo " help this help"
> - @echo " sysroot create the nolibc sysroot here (uses \$$ARCH)"
> - @echo " nolibc-test build the executable (uses \$$CC and \$$CROSS_COMPILE)"
> - @echo " libc-test build an executable using the compiler's default libc instead"
> - @echo " run-user runs the executable under QEMU (uses \$$XARCH, \$$TEST)"
> - @echo " initramfs prepare the initramfs with nolibc-test"
> - @echo " defconfig create a fresh new default config (uses \$$XARCH)"
> - @echo " kernel (re)build the kernel with the initramfs (uses \$$XARCH)"
> - @echo " run runs the kernel in QEMU after building it (uses \$$XARCH, \$$TEST)"
> - @echo " rerun runs a previously prebuilt kernel in QEMU (uses \$$XARCH, \$$TEST)"
> - @echo " clean clean the sysroot, initramfs, build and output files"
> + @echo " all call the \"run\" target below"
> + @echo " help this help"
> + @echo " sysroot create the nolibc sysroot here (uses \$$ARCH)"
> + @echo " nolibc-test build the executable (uses \$$CC and \$$CROSS_COMPILE)"
> + @echo " libc-test build an executable using the compiler's default libc instead"
> + @echo " run-user runs the executable under QEMU (uses \$$XARCH, \$$TEST)"
> + @echo " initramfs.cpio prepare the initramfs archive with nolibc-test"
> + @echo " initramfs prepare the initramfs tree with nolibc-test"
> + @echo " defconfig create a fresh new default config (uses \$$XARCH)"
> + @echo " kernel (re)build the kernel (uses \$$XARCH)"
> + @echo " kernel-standalone (re)build the kernel with the initramfs (uses \$$XARCH)"
> + @echo " run runs the kernel in QEMU after building it (uses \$$XARCH, \$$TEST)"
> + @echo " rerun runs a previously prebuilt kernel in QEMU (uses \$$XARCH, \$$TEST)"
> + @echo " clean clean the sysroot, initramfs, build and output files"
> @echo ""
> @echo "The output file is \"run.out\". Test ranges may be passed using \$$TEST."
> @echo ""
> @@ -195,6 +197,9 @@ run-user: nolibc-test
> $(Q)qemu-$(QEMU_ARCH) ./nolibc-test > "$(CURDIR)/run.out" || :
> $(Q)$(REPORT) $(CURDIR)/run.out
>
> +initramfs.cpio: kernel nolibc-test
> + $(QUIET_GEN)echo 'file /init nolibc-test 755 0 0' | $(srctree)/usr/gen_init_cpio - > initramfs.cpio
> +
> initramfs: nolibc-test
> $(QUIET_MKDIR)mkdir -p initramfs
> $(call QUIET_INSTALL, initramfs/init)
> @@ -203,17 +208,20 @@ initramfs: nolibc-test
> defconfig:
> $(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) mrproper $(DEFCONFIG) prepare
>
> -kernel: initramfs
> +kernel:
> + $(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME)
> +
> +kernel-standalone: initramfs
> $(Q)$(MAKE) -C $(srctree) ARCH=$(ARCH) CC=$(CC) CROSS_COMPILE=$(CROSS_COMPILE) $(IMAGE_NAME) CONFIG_INITRAMFS_SOURCE=$(CURDIR)/initramfs
>
> # run the tests after building the kernel
> -run: kernel
> - $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
> +run: kernel initramfs.cpio
> + $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -initrd initramfs.cpio -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
> $(Q)$(REPORT) $(CURDIR)/run.out
>
> # re-run the tests from an existing kernel
> rerun:
> - $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
> + $(Q)qemu-system-$(QEMU_ARCH) -display none -no-reboot -kernel "$(srctree)/$(IMAGE)" -initrd initramfs.cpio -serial stdio $(QEMU_ARGS) > "$(CURDIR)/run.out"
> $(Q)$(REPORT) $(CURDIR)/run.out
>
> # report with existing test log
> @@ -227,6 +235,8 @@ clean:
> $(Q)rm -f nolibc-test
> $(call QUIET_CLEAN, libc-test)
> $(Q)rm -f libc-test
> + $(call QUIET_CLEAN, initramfs.cpio)
> + $(Q)rm -rf initramfs.cpio
> $(call QUIET_CLEAN, initramfs)
> $(Q)rm -rf initramfs
> $(call QUIET_CLEAN, run.out)
>
> ---
> base-commit: 3f79a57865b33f49fdae6655510bd27c8e6610e0
> change-id: 20230916-nolibc-initramfs-4fd00eac3256
>
> Best regards,
> --
> Thomas Weißschuh <linux@weissschuh.net>
--
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2023-09-17 15:21 [PATCH RFC v2] selftests/nolibc: don't embed initramfs into kernel image Thomas Weißschuh
2023-09-18 16:20 ` Willy Tarreau
2023-09-19 11:47 ` Nicolas Schier
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