Re: next/master bisection: baseline.dmesg.crit on qemu_arm-vexpress-a15

From: Andre Przywara
Date: Mon Jun 29 2020 - 17:03:30 EST

On 26/06/2020 21:23, Guillaume Tucker wrote:

Hi,

> On 26/06/2020 20:11, kernelci.org bot wrote:
>> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>> * This automated bisection report was sent to you on the basis *
>> * that you may be involved with the breaking commit it has *
>> * found. No manual investigation has been done to verify it, *
>> * and the root cause of the problem may be somewhere else. *
>> * *
>> * If you do send a fix, please include this trailer: *
>> * Reported-by: "kernelci.org bot" <bot@xxxxxxxxxxxx> *
>> * *
>> * Hope this helps! *
>> * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * *
>>
>> next/master bisection: baseline.dmesg.crit on qemu_arm-vexpress-a15
>>
>> Summary:
>> Start: 36e3135df4d4 Add linux-next specific files for 20200626
>> Plain log: https://storage.kernelci.org/next/master/next-20200626/arm/vexpress_defconfig/gcc-8/lab-collabora/baseline-vexpress-v2p-ca15-tc1.txt
>> HTML log: https://storage.kernelci.org/next/master/next-20200626/arm/vexpress_defconfig/gcc-8/lab-collabora/baseline-vexpress-v2p-ca15-tc1.html
>> Result: 38ac46002d1d arm: dts: vexpress: Move mcc node back into motherboard node
>>
>> Checks:
>> revert: PASS
>> verify: PASS
>>
>> Parameters:
>> Tree: next
>> URL: https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
>> Branch: master
>> Target: qemu_arm-vexpress-a15
>> CPU arch: arm
>> Lab: lab-collabora
>> Compiler: gcc-8
>> Config: vexpress_defconfig
>> Test case: baseline.dmesg.crit
>
> The critical error message allegedly caused by this commit is:
>
> <2>GIC CPU mask not found - kernel will fail to boot.
>
> The report needs to be improved to show it automatically, sorry
> if this wasn't clear.

No worries, I saw this. But more important is this message:
13:53:51.773784 <6>smp: Bringing up secondary CPUs ...
13:53:51.774587 <3>CPU1: failed to boot: -38

And this points to the actual problem: The QEMU command line according
to the log is not specifying an "-smp" argument, so QEMU defaults to one
core. Now we force a .dtb on it, which describes two cores - because
this is what the actual hardware has. This won't go well, QEMU will deny
to online a second core.

So I don't see how this ever worked, regardless of this patch.
I tested this here, which a slightly different QEMU cmdline to run on my
box:
qemu-system-arm -m 512 -cpu cortex-a15 -machine vexpress-a15 -dtb
vexpress-v2p-ca15-tc1.dtb-5.8-next -nographic -kernel zImage-5.8-next
-append "console=ttyAMA0 earlycon=pl011,0x1c090000 debug" -initrd
initrd-armhf.img.gz
I get the same GIC complaint and only one core coming online. If I
however add "-smp 2" to the QEMU command line, everything works fine: no
GIC messages, and the second core comes up.

I did the test with v5.7, v5.8-rc2, v5.8-rc3 and linux-next, all with
the same result (ignoring the bug in 5.8-rc2 that this patch here fixes).

So can someone shed some light on what is going on here? Is there some
bootlog that does not have the GIC messages and brings up the second
core, with the same QEMU command line?

Cheers,
Andre

>> Breaking commit found:
>>
>> -------------------------------------------------------------------------------
>> commit 38ac46002d1df5707566a73486452851341028d2
>> Author: Andre Przywara <andre.przywara@xxxxxxx>
>> Date: Wed Jun 3 17:22:37 2020 +0100
>>
>> arm: dts: vexpress: Move mcc node back into motherboard node
>>
>> Commit d9258898ad49 ("arm64: dts: arm: vexpress: Move fixed devices
>> out of bus node") moved the "mcc" DT node into the root node, because
>> it does not have any children using "reg" properties, so does violate
>> some dtc checks about "simple-bus" nodes.
>>
>> However this broke the vexpress config-bus code, which walks up the
>> device tree to find the first node with an "arm,vexpress,site" property.
>> This gave the wrong result (matching the root node instead of the
>> motherboard node), so broke the clocks and some other devices for
>> VExpress boards.
>>
>> Move the whole node back into its original position. This re-introduces
>> the dtc warning, but is conceptually the right thing to do. The dtc
>> warning seems to be overzealous here, there are discussions on fixing or
>> relaxing this check instead.
>>
>> Link: https://lore.kernel.org/r/20200603162237.16319-1-andre.przywara@xxxxxxx
>> Fixes: d9258898ad49 ("arm64: dts: vexpress: Move fixed devices out of bus node")
>> Reported-and-tested-by: Guenter Roeck <linux@xxxxxxxxxxxx>
>> Signed-off-by: Andre Przywara <andre.przywara@xxxxxxx>
>> Signed-off-by: Sudeep Holla <sudeep.holla@xxxxxxx>
>>
>> diff --git a/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi b/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi
>> index e6308fb76183..a88ee5294d35 100644
>> --- a/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi
>> +++ b/arch/arm/boot/dts/vexpress-v2m-rs1.dtsi
>> @@ -100,79 +100,6 @@
>> };
>> };
>>
>> - mcc {
>> - compatible = "arm,vexpress,config-bus";
>> - arm,vexpress,config-bridge = <&v2m_sysreg>;
>> -
>> - oscclk0 {
>> - /* MCC static memory clock */
>> - compatible = "arm,vexpress-osc";
>> - arm,vexpress-sysreg,func = <1 0>;
>> - freq-range = <25000000 60000000>;
>> - #clock-cells = <0>;
>> - clock-output-names = "v2m:oscclk0";
>> - };
>> -
>> - v2m_oscclk1: oscclk1 {
>> - /* CLCD clock */
>> - compatible = "arm,vexpress-osc";
>> - arm,vexpress-sysreg,func = <1 1>;
>> - freq-range = <23750000 65000000>;
>> - #clock-cells = <0>;
>> - clock-output-names = "v2m:oscclk1";
>> - };
>> -
>> - v2m_oscclk2: oscclk2 {
>> - /* IO FPGA peripheral clock */
>> - compatible = "arm,vexpress-osc";
>> - arm,vexpress-sysreg,func = <1 2>;
>> - freq-range = <24000000 24000000>;
>> - #clock-cells = <0>;
>> - clock-output-names = "v2m:oscclk2";
>> - };
>> -
>> - volt-vio {
>> - /* Logic level voltage */
>> - compatible = "arm,vexpress-volt";
>> - arm,vexpress-sysreg,func = <2 0>;
>> - regulator-name = "VIO";
>> - regulator-always-on;
>> - label = "VIO";
>> - };
>> -
>> - temp-mcc {
>> - /* MCC internal operating temperature */
>> - compatible = "arm,vexpress-temp";
>> - arm,vexpress-sysreg,func = <4 0>;
>> - label = "MCC";
>> - };
>> -
>> - reset {
>> - compatible = "arm,vexpress-reset";
>> - arm,vexpress-sysreg,func = <5 0>;
>> - };
>> -
>> - muxfpga {
>> - compatible = "arm,vexpress-muxfpga";
>> - arm,vexpress-sysreg,func = <7 0>;
>> - };
>> -
>> - shutdown {
>> - compatible = "arm,vexpress-shutdown";
>> - arm,vexpress-sysreg,func = <8 0>;
>> - };
>> -
>> - reboot {
>> - compatible = "arm,vexpress-reboot";
>> - arm,vexpress-sysreg,func = <9 0>;
>> - };
>> -
>> - dvimode {
>> - compatible = "arm,vexpress-dvimode";
>> - arm,vexpress-sysreg,func = <11 0>;
>> - };
>> - };
>> -
>> bus@8000000 {
>> motherboard-bus {
>> model = "V2M-P1";
>> @@ -435,6 +362,79 @@
>> };
>> };
>> };
>> +
>> + mcc {
>> + compatible = "arm,vexpress,config-bus";
>> + arm,vexpress,config-bridge = <&v2m_sysreg>;
>> +
>> + oscclk0 {
>> + /* MCC static memory clock */
>> + compatible = "arm,vexpress-osc";
>> + arm,vexpress-sysreg,func = <1 0>;
>> + freq-range = <25000000 60000000>;
>> + #clock-cells = <0>;
>> + clock-output-names = "v2m:oscclk0";
>> + };
>> +
>> + v2m_oscclk1: oscclk1 {
>> + /* CLCD clock */
>> + compatible = "arm,vexpress-osc";
>> + arm,vexpress-sysreg,func = <1 1>;
>> + freq-range = <23750000 65000000>;
>> + #clock-cells = <0>;
>> + clock-output-names = "v2m:oscclk1";
>> + };
>> +
>> + v2m_oscclk2: oscclk2 {
>> + /* IO FPGA peripheral clock */
>> + compatible = "arm,vexpress-osc";
>> + arm,vexpress-sysreg,func = <1 2>;
>> + freq-range = <24000000 24000000>;
>> + #clock-cells = <0>;
>> + clock-output-names = "v2m:oscclk2";
>> + };
>> +
>> + volt-vio {
>> + /* Logic level voltage */
>> + compatible = "arm,vexpress-volt";
>> + arm,vexpress-sysreg,func = <2 0>;
>> + regulator-name = "VIO";
>> + regulator-always-on;
>> + label = "VIO";
>> + };
>> +
>> + temp-mcc {
>> + /* MCC internal operating temperature */
>> + compatible = "arm,vexpress-temp";
>> + arm,vexpress-sysreg,func = <4 0>;
>> + label = "MCC";
>> + };
>> +
>> + reset {
>> + compatible = "arm,vexpress-reset";
>> + arm,vexpress-sysreg,func = <5 0>;
>> + };
>> +
>> + muxfpga {
>> + compatible = "arm,vexpress-muxfpga";
>> + arm,vexpress-sysreg,func = <7 0>;
>> + };
>> +
>> + shutdown {
>> + compatible = "arm,vexpress-shutdown";
>> + arm,vexpress-sysreg,func = <8 0>;
>> + };
>> +
>> + reboot {
>> + compatible = "arm,vexpress-reboot";
>> + arm,vexpress-sysreg,func = <9 0>;
>> + };
>> +
>> + dvimode {
>> + compatible = "arm,vexpress-dvimode";
>> + arm,vexpress-sysreg,func = <11 0>;
>> + };
>> + };
>> };
>> };
>> };
>> -------------------------------------------------------------------------------
>>
>>
>> Git bisection log:
>>
>> -------------------------------------------------------------------------------
>> git bisect start
>> # good: [52366a107bf0600cf366f5ff3ea1f147b285e41f] Merge tag 'fsnotify_for_v5.8-rc3' of git://git.kernel.org/pub/scm/linux/kernel/git/jack/linux-fs
>> git bisect good 52366a107bf0600cf366f5ff3ea1f147b285e41f
>> # bad: [36e3135df4d426612fc77db26a312c2531108603] Add linux-next specific files for 20200626
>> git bisect bad 36e3135df4d426612fc77db26a312c2531108603
>> # bad: [11fdea666694c5c8c8a52cb75b2f0e70a2c2c201] Merge remote-tracking branch 'drm/drm-next'
>> git bisect bad 11fdea666694c5c8c8a52cb75b2f0e70a2c2c201
>> # bad: [39ac1a242d0940dabd9192d99113c2b082ba45bc] Merge remote-tracking branch 'printk/for-next'
>> git bisect bad 39ac1a242d0940dabd9192d99113c2b082ba45bc
>> # good: [4a750150d9fe543e2163998501b3ad947d6dff74] Merge remote-tracking branch 'at91/at91-next'
>> git bisect good 4a750150d9fe543e2163998501b3ad947d6dff74
>> # bad: [d7645ac1101c5160a05e2dced672a8d63c2a7ec0] Merge remote-tracking branch 'scmi/for-linux-next'
>> git bisect bad d7645ac1101c5160a05e2dced672a8d63c2a7ec0
>> # good: [2408a915a05c109169ab689dc91ce31315406513] Merge branches 'arm64-defconfig-for-5.9', 'arm64-for-5.9', 'drivers-for-5.9' and 'dts-for-5.9' into for-next
>> git bisect good 2408a915a05c109169ab689dc91ce31315406513
>> # good: [1679681fb8b2d169ac9d98660d7390620990bf77] Merge remote-tracking branch 'raspberrypi/for-next'
>> git bisect good 1679681fb8b2d169ac9d98660d7390620990bf77
>> # good: [137233bdcd265762a251dfa24e82ebc5468e0ec2] Merge remote-tracking branch 'reset/reset/next'
>> git bisect good 137233bdcd265762a251dfa24e82ebc5468e0ec2
>> # good: [99bcf38dd05b76b41f8564b53d9be6b44613fa92] Merge branch 'v5.9-clk/next' into for-next
>> git bisect good 99bcf38dd05b76b41f8564b53d9be6b44613fa92
>> # good: [dc45e438fac0b5df3c31bb83f3d809cd0f67dcfe] Merge branch 'next/dt' into for-next
>> git bisect good dc45e438fac0b5df3c31bb83f3d809cd0f67dcfe
>> # good: [d6fe116541b73a56110310c39a270c99766cd909] Merge branch 'next/soc' into for-next
>> git bisect good d6fe116541b73a56110310c39a270c99766cd909
>> # bad: [24077bf8f9e69a3a6a2c714634e6c813566a152f] Merge tag 'juno-fix-5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/sudeep.holla/linux into for-linux-next
>> git bisect bad 24077bf8f9e69a3a6a2c714634e6c813566a152f
>> # bad: [38ac46002d1df5707566a73486452851341028d2] arm: dts: vexpress: Move mcc node back into motherboard node
>> git bisect bad 38ac46002d1df5707566a73486452851341028d2
>> # first bad commit: [38ac46002d1df5707566a73486452851341028d2] arm: dts: vexpress: Move mcc node back into motherboard node
>> -------------------------------------------------------------------------------
>>
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