[Buildroot] [PATCH] package/swupdate: workaround runtime update failure

[Buildroot] [PATCH] package/swupdate: workaround runtime update failure

[Giulio Benetti]

From: Giulio Benetti <giulio.benetti+tekvox@benettiengineering.com>

If SWUpdate is built using -Os optimization it will fail to update using
Mongoose webserver randomly and always while using option
installed-directly in .swu file generation. So let's workaround the bug
by building with -O3.

Reported upstream:
https://groups.google.com/g/swupdate/c/oHMihNw8ZHA

Cc: Jim Reinhart <jimr@tekvox.com>
Cc: James Autry <jautry@tekvox.com>
Cc: Matthew Maron <matthewm@tekvox.com>
Signed-off-by: Giulio Benetti <giulio.benetti+tekvox@benettiengineering.com>
Signed-off-by: Giulio Benetti <giulio.benetti@benettiengineering.com>
---
 package/swupdate/swupdate.mk | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/package/swupdate/swupdate.mk b/package/swupdate/swupdate.mk
index ea4a5a62e5..7801be07ce 100644
--- a/package/swupdate/swupdate.mk
+++ b/package/swupdate/swupdate.mk
@@ -217,10 +217,19 @@ endif
 SWUPDATE_KCONFIG_FILE = $(call qstrip,$(BR2_PACKAGE_SWUPDATE_CONFIG))
 SWUPDATE_KCONFIG_EDITORS = menuconfig xconfig gconfig nconfig
 
+SWUPDATE_CFLAGS = $(TARGET_CFLAGS)
+
+# Workaround update failure showing up with -Os
+# Reported here:
+# https://groups.google.com/g/swupdate/c/oHMihNw8ZHA
+ifeq ($(BR2_OPTIMIZE_S),y)
+SWUPDATE_CFLAGS += -O3
+endif
+
 SWUPDATE_MAKE_OPTS = \
 	SWU_VER="$(SWUPDATE_VERSION) (Buildroot $(BR2_VERSION_FULL))" \
 	CROSS_COMPILE="$(TARGET_CROSS)" \
-	CONFIG_EXTRA_CFLAGS="$(TARGET_CFLAGS)" \
+	CONFIG_EXTRA_CFLAGS="$(SWUPDATE_CFLAGS)" \
 	CONFIG_EXTRA_LDFLAGS="$(TARGET_LDFLAGS)"
 
 define SWUPDATE_KCONFIG_FIXUP_CMDS
-- 
2.34.1

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Re: [Buildroot] [PATCH] package/swupdate: workaround runtime update failure

[Thomas Petazzoni via buildroot]

On Thu, 23 Nov 2023 18:39:57 +0100
Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:

> +SWUPDATE_CFLAGS = $(TARGET_CFLAGS)
> +
> +# Workaround update failure showing up with -Os
> +# Reported here:
> +# https://groups.google.com/g/swupdate/c/oHMihNw8ZHA
> +ifeq ($(BR2_OPTIMIZE_S),y)
> +SWUPDATE_CFLAGS += -O3
> +endif

This looks really horrible to me. Is there a compiler bug? Or a bug in
the swupdate code base, such as some undefined behavior that causes an
incorrect behavior when built -Os, but not -O3 ?

Thomas
-- 
Thomas Petazzoni, co-owner and CEO, Bootlin
Embedded Linux and Kernel engineering and training
https://bootlin.com
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Re: [Buildroot] [PATCH] package/swupdate: workaround runtime update failure

[Giulio Benetti]

Hi Thomas,

On 24/11/23 22:59, Thomas Petazzoni wrote:
> On Thu, 23 Nov 2023 18:39:57 +0100
> Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:
> 
>> +SWUPDATE_CFLAGS = $(TARGET_CFLAGS)
>> +
>> +# Workaround update failure showing up with -Os
>> +# Reported here:
>> +# https://groups.google.com/g/swupdate/c/oHMihNw8ZHA
>> +ifeq ($(BR2_OPTIMIZE_S),y)
>> +SWUPDATE_CFLAGS += -O3
>> +endif
> 
> This looks really horrible to me.

You're right,

> Is there a compiler bug? Or a bug in
> the swupdate code base, such as some undefined behavior that causes an
> incorrect behavior when built -Os, but not -O3 ?

An undefined behavior showing up when built with -Os, but I'm currently
trying to work it out and also to give a test case to SWUpdate
Maintainer using qemu-arm.

So I think it's better I get to the root cause, I fix it and later
provide a local patch to fix the problem.

I've already set the patch as Rejected on Patchwork, sorry for the
noise.

Best regards
-- 
Giulio Benetti
CEO&CTO@Benetti Engineering sas

> Thomas

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Re: [Buildroot] [PATCH] package/swupdate: workaround runtime update failure

[Thomas Petazzoni via buildroot]

Hello Giulio,

On Sat, 25 Nov 2023 01:24:45 +0100
Giulio Benetti <giulio.benetti@benettiengineering.com> wrote:

> > Is there a compiler bug? Or a bug in
> > the swupdate code base, such as some undefined behavior that causes an
> > incorrect behavior when built -Os, but not -O3 ?  
> 
> An undefined behavior showing up when built with -Os, but I'm currently
> trying to work it out and also to give a test case to SWUpdate
> Maintainer using qemu-arm.
> 
> So I think it's better I get to the root cause, I fix it and later
> provide a local patch to fix the problem.

Sounds good, thanks for the effort.

> I've already set the patch as Rejected on Patchwork, sorry for the
> noise.

No worries at all!

Best regards,

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