[PATCH] ARM: dts: meson8b: add reserved memory zone to fix silent freezes

On Mon, Oct 23, 2017 at 09:47:21AM +0200, Linus L?ssing wrote:

I'm currently continuing to bisect which difference in Emiliano's
and my kernel image makes mine boot successfully but not
Emiliano's. (And I'm continuing reading and testing with the
filter-range option to better understand what it's presence - or
absence - does exactly)

I found the difference between Emiliano's and my kernel image and
could narrow it down to this particular difference via bisecting:

Using the multi_v7_defconfig target, but with the following
two options unselected:

* System Type
  -> Qualcomm Support
     - Enable support for MSM8X60 (disabled)
     - Enable support for MSM8960 (disabled)

Results in the following diff, according to ./scripts/diffconfig:

-CLKSRC_QCOM y
-MSM_IOMMU n
 ARCH_MSM8960 y -> n
 ARCH_MSM8X60 y -> n

Once this is unselected, the kernel hangs for me on boot, too.
Both with or without this 2MB reserved memory region patch.

Removing the "arm,filter-ranges" as tried by Emiliano makes it
boot again.

Finally, what also helps booting again is this diff from the
pending SMP support patch series from Carlo/Martin [0]:

~~~~~

diff --git a/arch/arm/Makefile b/arch/arm/Makefile
index 47d3a1ab08d2..82faa958ab88 100644
--- a/arch/arm/Makefile
+++ b/arch/arm/Makefile

@@ -147,6 +147,7 @@  textofs-$(CONFIG_SA1111) := 0x00208000
 endif
 textofs-$(CONFIG_ARCH_MSM8X60) := 0x00208000
 textofs-$(CONFIG_ARCH_MSM8960) := 0x00208000
+textofs-$(CONFIG_ARCH_MESON) := 0x00208000
 textofs-$(CONFIG_ARCH_AXXIA) := 0x00308000
 
 # Machine directory name.  This list is sorted alphanumerically

~~~~~

Note the $(CONFIG_ARCH_MSM8X60) and $(CONFIG_ARCH_MSM8960) just
above. Sounds familiar :-)?

With this textofs diff alone, stress-ng still hangs though. Only
with the 2MB memory zone reserved via DT or the "arm,filter-ranges"
removed, stress-ng succeeds, too.

Regards, Linus

[0]: "[v7,4/6] ARM: meson: Add SMP bringup code for Meson8 and Meson8b"
     -> https://patchwork.kernel.org/patch/9954935/


On Mon, Oct 23, 2017 at 09:47:21AM +0200, Linus L?ssing wrote:

Subject: Re: [PATCH] ARM: dts: meson8b: add reserved memory zone to fix silent freezes
To: Kevin Hilman <khilman@baylibre.com>
Cc: Carlo Caione <redacted>, Kevin Hilman <khilman@baylibre.com>, Martin Blumenstingl <martin.blumenstingl@googlemail.com>, Emiliano Ingrassia <redacted>, linux-amlogic at lists.infradead.org

Hi Kevin,

Just wanted to let you know that Emiliano and I are currently
debugging further off-list.

So far I can reproduce that:

a) For the binary kernel image Emiliano sent me I can reproduce
his hang ups during boot on my Odroid C1+.
b) The 2MB reserved memory region this patch adds does not help
for this image.
c) Removing the "arm,filter-range" as proposed by Emiliano back
then instead of adding this reserved memory zone fixes my freezes
during boot in Emiliano's image and during stress-ng for my kernel
image, too.

I'm currently continuing to bisect which difference in Emiliano's
and my kernel image makes mine boot successfully but not
Emiliano's. (And I'm continuing reading and testing with the
filter-range option to better understand what it's presence - or
absence - does exactly)


If these observations ring a bell for anyone here, I'd be curious
to hear what they think.

Regards, Linus

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