Re: [PATCH 0/2] of: unittest: add overlay gpio test to catch gpio hog problem

From: Frank Rowand
Date: Wed Jan 29 2020 - 01:02:04 EST


On 1/28/20 11:46 PM, frowand.list@xxxxxxxxx wrote:
> From: Frank Rowand <frank.rowand@xxxxxxxx>
>
> Geert reports that gpio hog nodes are not properly processed when
> the gpio hog node is added via an overlay reply and provides an
> RFC patch to fix the problem [1].
>
> Add a unittest that shows the problem. Unittest will report "1 failed"
> test before applying Geert's RFC patch and "0 failed" after applying
> Geert's RFC patch.
>
> I did not have a development system for which it would be easy to
> experiment with applying an overlay containing a gpio hog, so I
> instead created this unittest that uses a fake gpio node.
>
> Some tests in the devicetree unittests result in printk messages
> from the code being tested. It can be difficult to determine
> whether the messages are the result of unittest or are potentially
> reporting bugs that should be fixed. The most recent example of
> a person asking whether to be concerned about these messages is [2].
>
> Patch 2 adds annotations for all messages triggered by unittests,
> except KERN_DEBUG messages. (KERN_DEBUG is a special case due to the
> possible interaction of CONFIG_DYNAMIC_DEBUG.)
>
> The annotations added in patch 2/2 add a small amount of verbosity
> to the console output. I have created a proof of concept tool to
> explore (1) how test harnesses could use the annotations and
> (2) how to make the resulting console output easier to read and
> understand as a human being. The tool 'of_unittest_expect' is
> available at https://github.com/frowand/dt_tools
>
> The format of the annotations is expected to change when unittests
> are converted to use the kunit infrastructure when the broader
> testing community has an opportunity to discuss the implementation
> of annotations of test triggered messages.
>
> [1] https://lore.kernel.org/linux-devicetree/20191230133852.5890-1-geert+renesas@xxxxxxxxx/
> [2] https://lore.kernel.org/r/6021ac63-b5e0-ed3d-f964-7c6ef579cd68@xxxxxxxxxx
>
> Frank Rowand (2):
> of: unittest: add overlay gpio test to catch gpio hog problem
> of: unittest: annotate warnings triggered by unittest
>
> drivers/of/unittest-data/Makefile | 8 +-
> drivers/of/unittest-data/overlay_gpio_01.dts | 23 +
> drivers/of/unittest-data/overlay_gpio_02a.dts | 16 +
> drivers/of/unittest-data/overlay_gpio_02b.dts | 16 +
> drivers/of/unittest-data/overlay_gpio_03.dts | 23 +
> drivers/of/unittest-data/overlay_gpio_04a.dts | 16 +
> drivers/of/unittest-data/overlay_gpio_04b.dts | 16 +
> drivers/of/unittest.c | 630 ++++++++++++++++++++++++--
> 8 files changed, 717 insertions(+), 31 deletions(-)
> create mode 100644 drivers/of/unittest-data/overlay_gpio_01.dts
> create mode 100644 drivers/of/unittest-data/overlay_gpio_02a.dts
> create mode 100644 drivers/of/unittest-data/overlay_gpio_02b.dts
> create mode 100644 drivers/of/unittest-data/overlay_gpio_03.dts
> create mode 100644 drivers/of/unittest-data/overlay_gpio_04a.dts
> create mode 100644 drivers/of/unittest-data/overlay_gpio_04b.dts
>

Console output after patch 1/2, filtered by 'of_unittest_expect':

ndroid Bootloader - UART_DM Initialized!!!
[0] welcome to lk

[10] platform_init()
[10] target_init()
[10] Display Init: Start
[10] display_init(),target_id=10.
[30] Config MIPI_VIDEO_PANEL.
[30] Turn on MIPI_VIDEO_PANEL.
[50] Video lane tested successfully
[50] Display Init: Done
[80] Loading keystore failed status 5 [80] ERROR: scm_protect_keystore Failed[200] USB init ept @ 0xf96b000
[220] fastboot_init()
[220] udc_start()
[350] -- reset --
[350] -- portchange --
[460] -- reset --
[460] -- portchange --
[650] fastboot: processing commands
[780] fastboot: download:00f30800
[1270] fastboot: boot
[1290] Found Appeneded Flattened Device tree
[1290] cmdline: console=ttyMSM0,115200,n8 androidboot.hardware=qcom maxcpus=2 msm_rtb.filter=0x37 ehci-hcd.park=3 norandmaps androidboot.emmc=true androidboot.serialno=40081c41 androidboot.baseband=apq
[1310] Updating device tree: start
[1310] Updating device tree: done
[1320] booting linux @ 0x8000, ramdisk @ 0x2000000 (9533134), tags/device tree @ 0x1e00000
[1320] Turn off MIPI_VIDEO_PANEL.
[1320] Continuous splash enabled, keeping panel alive.
Booting Linux on physical CPU 0x0
Linux version 5.5.0-00001-gee85e8d1d8fe-dirty (frowand@xps8900) (gcc version 4.6.x-google 20120106 (prerelease) (GCC)) #6 SMP PREEMPT Tue Jan 28 23:00:59 CST 2020
CPU: ARMv7 Processor [512f06f0] revision 0 (ARMv7), cr=10c5787d
CPU: div instructions available: patching division code
CPU: PIPT / VIPT nonaliasing data cache, PIPT instruction cache
OF: fdt: Machine model: Qualcomm APQ8074 Dragonboard
Memory policy: Data cache writealloc
cma: Reserved 256 MiB at 0x70000000
percpu: Embedded 19 pages/cpu s48192 r8192 d21440 u77824
Built 1 zonelists, mobility grouping on. Total pages: 490240
Kernel command line: console=ttyMSM0,115200,n8 androidboot.hardware=qcom maxcpus=2 msm_rtb.filter=0x37 ehci-hcd.park=3 norandmaps androidboot.emmc=true androidboot.serialno=40081c41 androidboot.baseband=apq
Dentry cache hash table entries: 131072 (order: 7, 524288 bytes, linear)
Inode-cache hash table entries: 65536 (order: 6, 262144 bytes, linear)
mem auto-init: stack:off, heap alloc:off, heap free:off
Memory: 1664560K/1967104K available (8192K kernel code, 859K rwdata, 3788K rodata, 1024K init, 268K bss, 40400K reserved, 262144K cma-reserved, 1048576K highmem)
SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=4, Nodes=1
rcu: Preemptible hierarchical RCU implementation.
Tasks RCU enabled.
rcu: RCU calculated value of scheduler-enlistment delay is 10 jiffies.
NR_IRQS: 16, nr_irqs: 16, preallocated irqs: 16
random: get_random_bytes called from start_kernel+0x2fc/0x508 with crng_init=0
arch_timer: cp15 and mmio timer(s) running at 19.20MHz (virt/virt).
clocksource: arch_sys_counter: mask: 0xffffffffffffff max_cycles: 0x46d987e47, max_idle_ns: 440795202767 ns
sched_clock: 56 bits at 19MHz, resolution 52ns, wraps every 4398046511078ns
Switching to timer-based delay loop, resolution 52ns
Console: colour dummy device 80x30
Calibrating delay loop (skipped), value calculated using timer frequency.. 38.40 BogoMIPS (lpj=192000)
pid_max: default: 32768 minimum: 301
Mount-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
Mountpoint-cache hash table entries: 2048 (order: 1, 8192 bytes, linear)
CPU: Testing write buffer coherency: ok
CPU0: thread -1, cpu 0, socket 0, mpidr 80000000
Setting up static identity map for 0x300000 - 0x300060
rcu: Hierarchical SRCU implementation.
smp: Bringing up secondary CPUs ...
CPU1: thread -1, cpu 1, socket 0, mpidr 80000001
smp: Brought up 1 node, 2 CPUs
SMP: Total of 2 processors activated (76.80 BogoMIPS).
CPU: All CPU(s) started in SVC mode.
devtmpfs: initialized
VFP support v0.3: implementor 51 architecture 64 part 6f variant 2 rev 0
clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 19112604462750000 ns
futex hash table entries: 1024 (order: 4, 65536 bytes, linear)
pinctrl core: initialized pinctrl subsystem
thermal_sys: Registered thermal governor 'step_wise'
NET: Registered protocol family 16
DMA: preallocated 256 KiB pool for atomic coherent allocations
cpuidle: using governor menu
hw-breakpoint: found 5 (+1 reserved) breakpoint and 4 watchpoint registers.
hw-breakpoint: maximum watchpoint size is 8 bytes.
iommu: Default domain type: Translated
vgaarb: loaded
SCSI subsystem initialized
usbcore: registered new interface driver usbfs
usbcore: registered new interface driver hub
usbcore: registered new device driver usb
Advanced Linux Sound Architecture Driver Initialized.
clocksource: Switched to clocksource arch_sys_counter
NET: Registered protocol family 2
tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 6144 bytes, linear)
TCP established hash table entries: 8192 (order: 3, 32768 bytes, linear)
TCP bind hash table entries: 8192 (order: 4, 65536 bytes, linear)
TCP: Hash tables configured (established 8192 bind 8192)
UDP hash table entries: 512 (order: 2, 16384 bytes, linear)
UDP-Lite hash table entries: 512 (order: 2, 16384 bytes, linear)
NET: Registered protocol family 1
RPC: Registered named UNIX socket transport module.
RPC: Registered udp transport module.
RPC: Registered tcp transport module.
RPC: Registered tcp NFSv4.1 backchannel transport module.
PCI: CLS 0 bytes, default 64
Trying to unpack rootfs image as initramfs...
Freeing initrd memory: 9312K
hw perfevents: enabled with armv7_krait PMU driver, 5 counters available
Initialise system trusted keyrings
workingset: timestamp_bits=30 max_order=19 bucket_order=0
NFS: Registering the id_resolver key type
Key type id_resolver registered
Key type id_legacy registered
Key type cifs.idmap registered
jffs2: version 2.2. (NAND) Â 2001-2006 Red Hat, Inc.
fuse: init (API version 7.31)
Key type asymmetric registered
Asymmetric key parser 'x509' registered
bounce: pool size: 64 pages
Block layer SCSI generic (bsg) driver version 0.4 loaded (major 250)
io scheduler mq-deadline registered
io scheduler kyber registered
msm_serial f991e000.serial: msm_serial: detected port #0
msm_serial f991e000.serial: uartclk = 7372800
f991e000.serial: ttyMSM0 at MMIO 0xf991e000 (irq = 28, base_baud = 460800) is a MSM
msm_serial: console setup on port #0
printk: console [ttyMSM0] enabled
msm_serial: driver initialized
brd: module loaded
loop: module loaded
SCSI Media Changer driver v0.25
spmi spmi-0: PMIC arbiter version v1 (0x20000002)
s1: supplied by regulator-dummy
s2: supplied by regulator-dummy
s3: supplied by regulator-dummy
s4: Bringing 5100000uV into 5000000-5000000uV
l1: supplied by regulator-dummy
l2: supplied by regulator-dummy
l3: supplied by regulator-dummy
l4: supplied by regulator-dummy
l5: supplied by regulator-dummy
l6: supplied by regulator-dummy
l7: supplied by regulator-dummy
l8: supplied by regulator-dummy
l9: supplied by regulator-dummy
l10: supplied by regulator-dummy
l11: supplied by regulator-dummy
l12: supplied by regulator-dummy
l13: supplied by regulator-dummy
l14: supplied by regulator-dummy
l15: supplied by regulator-dummy
l16: supplied by regulator-dummy
l17: supplied by regulator-dummy
l18: supplied by regulator-dummy
l19: supplied by regulator-dummy
l20: supplied by regulator-dummy
l21: supplied by regulator-dummy
l22: supplied by regulator-dummy
l23: supplied by regulator-dummy
l24: supplied by regulator-dummy
lvs1: supplied by regulator-dummy
lvs2: supplied by regulator-dummy
lvs3: supplied by regulator-dummy
5vs1: supplied by s4
5vs2: supplied by s4
libphy: Fixed MDIO Bus: probed
SLIP: version 0.8.4-NET3.019-NEWTTY (dynamic channels, max=256) (6 bit encapsulation enabled).
CSLIP: code copyright 1989 Regents of the University of California.
usbcore: registered new interface driver ax88179_178a
usbcore: registered new interface driver cdc_ether
usbcore: registered new interface driver net1080
usbcore: registered new interface driver cdc_subset
usbcore: registered new interface driver cdc_ncm
ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
ehci-pci: EHCI PCI platform driver
usbcore: registered new interface driver cdc_acm
cdc_acm: USB Abstract Control Model driver for USB modems and ISDN adapters
rtc-pm8xxx fc4cf000.spmi:pm8941@0:rtc@6000: registered as rtc0
i2c /dev entries driver
qcom-smbb fc4cf000.spmi:pm8941@0:charger@1000: Initializing SMBB rev 3
otg-vbus: supplied by 5vs1
cpuidle: enable-method property 'qcom,kpss-acc-v2' found operations
cpuidle: enable-method property 'qcom,kpss-acc-v2' found operations
cpuidle: enable-method property 'qcom,kpss-acc-v2' found operations
cpuidle: enable-method property 'qcom,kpss-acc-v2' found operations
sdhci: Secure Digital Host Controller Interface driver
sdhci: Copyright(c) Pierre Ossman
sdhci-pltfm: SDHCI platform and OF driver helper
sdhci_msm f98a4900.sdhci: Got CD GPIO
usbcore: registered new interface driver usbhid
usbhid: USB HID core driver
oprofile: using timer interrupt.
NET: Registered protocol family 17
Key type dns_resolver registered
Registering SWP/SWPB emulation handler
Loading compiled-in X.509 certificates
debugfs: Directory 'fc4a9000.thermal-sensor' with parent 'tsens' already present!
sdhci_msm f98a4900.sdhci: Got CD GPIO
sdhci_msm f98a4900.sdhci: Got CD GPIO
s1: supplied by regulator-dummy
s1: Bringing 0uV into 675000-675000uV
sdhci_msm f98a4900.sdhci: Got CD GPIO
rtc-pm8xxx fc4cf000.spmi:pm8941@0:rtc@6000: setting system clock to 1970-01-16T23:55:43 UTC (1382143)
Duplicate name in testcase-data, renamed to "duplicate-name#1"
s2: supplied by regulator-dummy
-> ### dt-test ### start of unittest - you will see error messages
s2: Bringing 0uV into 500000-500000uV
OF: /testcase-data/phandle-tests/consumer-a: could not get #phandle-cells-missing for /testcase-data/phandle-tests/provider1
s3: supplied by regulator-dummy
OF: /testcase-data/phandle-tests/consumer-a: could not get #phandle-cells-missing for /testcase-data/phandle-tests/provider1
OF: /testcase-data/phandle-tests/consumer-a: could not find phandle
s3: Bringing 0uV into 500000-500000uV
OF: /testcase-data/phandle-tests/consumer-a: could not find phandle
s4: supplied by regulator-dummy
OF: /testcase-data/phandle-tests/consumer-a: #phandle-cells = 3 found -1
s4: Bringing 0uV into 500000-500000uV
OF: /testcase-data/phandle-tests/consumer-a: #phandle-cells = 3 found -1
s5: supplied by regulator-dummy
OF: /testcase-data/phandle-tests/consumer-b: could not get #phandle-missing-cells for /testcase-data/phandle-tests/provider1
s6: supplied by regulator-dummy
OF: /testcase-data/phandle-tests/consumer-b: could not find phandle
s7: supplied by regulator-dummy
OF: /testcase-data/phandle-tests/consumer-b: #phandle-cells = 2 found -1
s8: supplied by regulator-dummy
platform testcase-data:testcase-device2: IRQ index 0 not found
s1: supplied by regulator-dummy
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest0/status
s1: Bringing 0uV into 1300000-1300000uV
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest1/status
s2: supplied by regulator-dummy
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest2/status
s2: Bringing 0uV into 2150000-2150000uV
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest3/status
s3: supplied by regulator-dummy
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest5/status
sdhci_msm f98a4900.sdhci: Got CD GPIO
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest6/status
s3: Bringing 0uV into 1800000-1800000uV
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest7/status
l1: supplied by s1
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest8/status
sdhci_msm f98a4900.sdhci: Got CD GPIO
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/test-unittest8/property-foo
l1: Bringing 0uV into 1225000-1225000uV
OF: overlay: node_overlaps_later_cs: #6 overlaps with #7 @/testcase-data/overlay-node/test-bus/test-unittest8
OF: overlay: overlay #6 is not topmost
l2: supplied by s3
l2: Bringing 0uV into 1200000-1200000uV
l3: supplied by s1
i2c i2c-1: Added multiplexed i2c bus 2
sdhci_msm f98a4900.sdhci: Got CD GPIO
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/i2c-test-bus/test-unittest12/status
l3: Bringing 0uV into 1225000-1225000uV
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data/overlay-node/test-bus/i2c-test-bus/test-unittest13/status
l4: supplied by s1
i2c i2c-1: Added multiplexed i2c bus 3
sdhci_msm f98a4900.sdhci: Got CD GPIO
l4: Bringing 0uV into 1225000-1225000uV
l5: supplied by s2
ok GPIO line 315 (line-B-input) hogged as input
sdhci_msm f98a4900.sdhci: Got CD GPIO
ok GPIO line 309 (line-A-input) hogged as input
l5: Bringing 0uV into 1800000-1800000uV
l6: supplied by s2
l6: Bringing 0uV into 1800000-1800000uV
ok GPIO line 307 (line-D-input) hogged as input
l7: supplied by s2
sdhci_msm f98a4900.sdhci: Got CD GPIO
l7: Bringing 0uV into 1800000-1800000uV
** of_unittest_expect WARNING - not found ---> GPIO line <<int>> (line-C-input) hogged as input
l8: supplied by regulator-dummy
>> ### dt-test ### FAIL of_unittest_overlay_gpio():2424 unittest_gpio_chip_request() called 0 times (expected 1 time)
sdhci_msm f98a4900.sdhci: Got CD GPIO
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/substation@100/status
l8: Bringing 0uV into 1800000-1800000uV
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/fairway-1/status
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/fairway-1/ride@100/track@30/incline-up
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/fairway-1/ride@100/track@40/incline-up
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/lights@40000/status
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/lights@40000/color
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/lights@40000/rate
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /__symbols__/hvac_2
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /__symbols__/ride_200
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /__symbols__/ride_200_left
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /__symbols__/ride_200_right
OF: overlay: ERROR: multiple fragments add and/or delete node /testcase-data-2/substation@100/motor-1/controller
l9: supplied by regulator-dummy
l9: Bringing 0uV into 1800000-1800000uV
OF: overlay: ERROR: multiple fragments add, update, and/or delete property /testcase-data-2/substation@100/motor-1/controller/name
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/substation@100/motor-1/rpm_avail
OF: overlay: WARNING: memory leak will occur if overlay removed, property: /testcase-data-2/substation@100/motor-1/rpm_avail
OF: overlay: ERROR: multiple fragments add, update, and/or delete property /testcase-data-2/substation@100/motor-1/rpm_avail
-> ### dt-test ### end of unittest - 258 passed, 1 failed
l10: supplied by regulator-dummy
ALSA device list:
sdhci_msm f98a4900.sdhci: Got CD GPIO
No soundcardï[ 3.059465] l11: supplied by s1
l11: Bringing 0uV into 1300000-1300000uV
Freeing unused kernel memory: 1024K
l12: supplied by s2
l12: Bringing 0uV into 1800000-1800000uV
l13: supplied by regulator-dummy
l13: Bringing 0uV into 1800000-1800000uV
l14: supplied by s2
l14: Bringing 0uV into 1800000-1800000uV
l15: supplied by s2
l15: Bringing 0uV into 2050000-2050000uV
Run /init as init process
l16: supplied by regulator-dummy
l16: Bringing 0uV into 2700000-2700000uV
l17: supplied by regulator-dummy
l17: Bringing 0uV into 2700000-2700000uV
l18: supplied by regulator-dummy
l18: Bringing 0uV into 2850000-2850000uV
l19: supplied by regulator-dummy
l19: Bringing 0uV into 3300000-3300000uV
l20: supplied by regulator-dummy
l20: Bringing 0uV into 2950000-2950000uV
l21: supplied by regulator-dummy
l21: Bringing 0uV into 2950000-2950000uV
l22: supplied by regulator-dummy
l22: Bringing 0uV into 3000000-3000000uV
l23: supplied by regulator-dummy
l23: Bringing 0uV into 3000000-3000000uV
l24: supplied by regulator-dummy
l24: Bringing 0uV into 3075000-3075000uV
lvs1: supplied by s3
mkdir: can't create directory '/bin': File exists
mkdir: can't [ 3.194707] lvs2: supplied by s3
create directory '/dev': File exists
/init: line 25: can't crea[ 3.203415] lvs3: supplied by s3
te /proc/sys/kernel/hotplug: nonexistent directory
mdev: unknow[ 3.212141] 5vs1: supplied by s4
n user/group 'root:uucp' on line 34
5vs2: supplied by s4
mmc0: SDHCI controller on f9824900.sdhci [f9824900.sdhci] using ADMA
sdhci_msm f98a4900.sdhci: Got CD GPIO
mmc1: SDHCI controller on f98a4900.sdhci [f98a4900.sdhci] using ADMA
mmc0: new HS200 MMC card at address 0001
mmc1: new ultra high speed DDR50 SDHC card at address aaaa
mmcblk0: mmc0:0001 SEM16G 14.7 GiB
mmcblk0boot0: mmc0:0001 SEM16G partition 1 4.00 MiB
mmcblk0boot1: mmc0:0001 SEM16G partition 2 4.00 MiB
mmcblk1: mmc1:aaaa SU16G 14.8 GiB
mmcblk0rpmb: mmc0:0001 SEM16G partition 3 4.00 MiB, chardev (247:0)
mmcblk1: p1
mmcblk0: p1 p2 p3 p4 p5 p6 p7 p8 p9 p10 p11 p12 p13 p14 p15 p16 p17 p18 p19 p20
Attempt to mount partitions: /usr/system /usr/data
Mounting partitions from: /dev/mmcblk0
EXT4-fs (mmcblk0p12): mounted filesystem with ordered data mode. Opts: (null)
random: fast init done
EXT4-fs (mmcblk0p13): recovery complete
EXT4-fs (mmcblk0p13): mounted filesystem with ordered data mode. Opts: (null)
/ #
/ # cat /proc/version
Linux version 5.5.0-00001-gee85e8d1d8fe-dirty (frowand@xps8900) (gcc version 4.6.x-google 20120106 (prerelease) (GCC)) #6 SMP PREEMPT Tue Jan 28 23:00:59 CST 2020