Re: [PATCH v12 00/25] Linux RISC-V AIA Support

From: Anup Patel
Date: Tue Jan 30 2024 - 05:23:42 EST


On Tue, Jan 30, 2024 at 1:22 PM Björn Töpel <bjorn@kernelorg> wrote:
>
> Björn Töpel <bjorn@xxxxxxxxxx> writes:
>
> > Anup Patel <apatel@xxxxxxxxxxxxxxxx> writes:
> >
> >> The RISC-V AIA specification is ratified as-per the RISC-V international
> >> process. The latest ratified AIA specifcation can be found at:
> >> https://github.com/riscv/riscv-aia/releases/download/1.0/riscv-interrupts-1.0.pdf
> >>
> >> At a high-level, the AIA specification adds three things:
> >> 1) AIA CSRs
> >> - Improved local interrupt support
> >> 2) Incoming Message Signaled Interrupt Controller (IMSIC)
> >> - Per-HART MSI controller
> >> - Support MSI virtualization
> >> - Support IPI along with virtualization
> >> 3) Advanced Platform-Level Interrupt Controller (APLIC)
> >> - Wired interrupt controller
> >> - In MSI-mode, converts wired interrupt into MSIs (i.e. MSI generator)
> >> - In Direct-mode, injects external interrupts directly into HARTs
> >>
> >> For an overview of the AIA specification, refer the AIA virtualization
> >> talk at KVM Forum 2022:
> >> https://static.sched.com/hosted_files/kvmforum2022/a1/AIA_Virtualization_in_KVM_RISCV_final.pdf
> >> https://www.youtube.com/watch?v=r071dL8Z0yo
> >>
> >> To test this series, use QEMU v7.2 (or higher) and OpenSBI v1.2 (or higher).
> >>
> >> These patches can also be found in the riscv_aia_v12 branch at:
> >> https://github.com/avpatel/linux.git
> >>
> >> Changes since v11:
> >> - Rebased on Linux-6.8-rc1
> >> - Included kernel/irq related patches from "genirq, irqchip: Convert ARM
> >> MSI handling to per device MSI domains" series by Thomas.
> >> (PATCH7, PATCH8, PATCH9, PATCH14, PATCH16, PATCH17, PATCH18, PATCH19,
> >> PATCH20, PATCH21, PATCH22, PATCH23, and PATCH32 of
> >> https://lore.kernel.org/linux-arm-kernel/20221121135653.208611233@xxxxxxxxxxxxx/)
> >> - Updated APLIC MSI-mode driver to use the new WIRED_TO_MSI mechanism.
> >> - Updated IMSIC driver to support per-device MSI domains for PCI and
> >> platform devices.
> >
> > Thanks for working on this, Anup! I'm still reviewing the patches.
> >
> > I'm hitting a boot hang in text patching, with this series applied on
> > 6.8-rc2. IPI issues?
>
> Not text patching! One cpu spinning in smp_call_function_many_cond() and
> the others are in cpu_relax(). Smells like IPI...

I tried bootefi from U-Boot multiple times but can't reproduce the
issue you are seeing.

Here's my boot log ...

$ qemu-system-riscv64 -M virt,aia=aplic-imsic -m 256M -display none
-serial stdio -bios
opensbi/build/platform/generic/firmware/fw_jump.bin -kernel
/u-boot/u-boot.bin -device
loader,file=./build-riscv64/arch/riscv/boot/Image,addr=0x84000000
-drive file=./rootfs_riscv64.ext2,format=raw,id=hd0 -device
virtio-blk-device,drive=hd0 -device virtio-net-device,netdev=eth0
-netdev user,id=eth0 -object rng-random,filename=/dev/urandom,id=rng0
-device virtio-rng-device,rng=rng0 -append "root=/dev/vda rootwait rw
console=ttyS0 earlycon" -smp 8

OpenSBI v1.4-8-gbb90a9e
____ _____ ____ _____
/ __ \ / ____| _ \_ _|
| | | |_ __ ___ _ __ | (___ | |_) || |
| | | | '_ \ / _ \ '_ \ \___ \| _ < | |
| |__| | |_) | __/ | | |____) | |_) || |_
\____/| .__/ \___|_| |_|_____/|____/_____|
| |
|_|

Platform Name : riscv-virtio,qemu
Platform Features : medeleg
Platform HART Count : 8
Platform IPI Device : aia-imsic
Platform Timer Device : aclint-mtimer @ 10000000Hz
Platform Console Device : uart8250
Platform HSM Device : ---
Platform PMU Device : ---
Platform Reboot Device : syscon-reboot
Platform Shutdown Device : syscon-poweroff
Platform Suspend Device : ---
Platform CPPC Device : ---
Firmware Base : 0x80000000
Firmware Size : 395 KB
Firmware RW Offset : 0x40000
Firmware RW Size : 139 KB
Firmware Heap Offset : 0x56000
Firmware Heap Size : 51 KB (total), 3 KB (reserved), 12 KB
(used), 36 KB (free)
Firmware Scratch Size : 4096 B (total), 328 B (used), 3768 B (free)
Runtime SBI Version : 2.0

Domain0 Name : root
Domain0 Boot HART : 7
Domain0 HARTs : 0*,1*,2*,3*,4*,5*,6*,7*
Domain0 Region00 : 0x0000000000100000-0x0000000000100fff M:
(I,R,W) S/U: (R,W)
Domain0 Region01 : 0x0000000010000000-0x0000000010000fff M:
(I,R,W) S/U: (R,W)
Domain0 Region02 : 0x000000000c000000-0x000000000c007fff M:
(I,R,W) S/U: ()
Domain0 Region03 : 0x0000000024000000-0x0000000024007fff M:
(I,R,W) S/U: ()
Domain0 Region04 : 0x0000000002000000-0x000000000200ffff M:
(I,R,W) S/U: ()
Domain0 Region05 : 0x0000000080000000-0x000000008003ffff M:
(R,X) S/U: ()
Domain0 Region06 : 0x0000000080040000-0x000000008007ffff M:
(R,W) S/U: ()
Domain0 Region07 : 0x0000000000000000-0xffffffffffffffff M:
() S/U: (R,W,X)
Domain0 Next Address : 0x0000000080200000
Domain0 Next Arg1 : 0x0000000082200000
Domain0 Next Mode : S-mode
Domain0 SysReset : yes
Domain0 SysSuspend : yes

Boot HART ID : 7
Boot HART Domain : root
Boot HART Priv Version : v1.12
Boot HART Base ISA : rv64imafdch
Boot HART ISA Extensions : smaia,sstc,zicntr,zihpm,zicboz,zicbom,sdtrig
Boot HART PMP Count : 16
Boot HART PMP Granularity : 2 bits
Boot HART PMP Address Bits: 54
Boot HART MHPM Info : 16 (0x0007fff8)
Boot HART Debug Triggers : 2 triggers
Boot HART MIDELEG : 0x0000000000001666
Boot HART MEDELEG : 0x0000000000f0b509


U-Boot 2023.10 (Nov 07 2023 - 18:28:29 +0530)

CPU: rv64imafdch_zicbom_zicboz_zicntr_zicsr_zifencei_zihintntl_zihintpause_zihpm_zawrs_zfa_zca_zcd_zba_zbb_zbc_zbs_smaia_ssaia_sstc_svadu
Model: riscv-virtio,qemu
DRAM: 256 MiB
Core: 37 devices, 16 uclasses, devicetree: board
Flash: 32 MiB
Loading Environment from nowhere... OK
In: serial,usbkbd
Out: serial,vidconsole
Err: serial,vidconsole
No working controllers found
Net: eth0: virtio-net#1
Working FDT set to 8ef1f870
Hit any key to stop autoboot: 0
=> bootefi ${kernel_addr_r}:0x1600000 ${fdtcontroladdr}
No EFI system partition
No EFI system partition
Failed to persist EFI variables
Booting /MemoryMapped(0x0,0x84000000,0x1600000)
EFI stub: Booting Linux Kernel...
EFI stub: Using DTB from configuration table
EFI stub: Exiting boot services...
[ 0.000000] Linux version 6.8.0-rc1-00039-gd9b9d6eb987f
(anup@anup-ubuntu-vm) (riscv64-unknown-linux-gnu-gcc (g2ee5e430018)
12.2.0, GNU ld (GNU Binutils) 2.40.0.20230214) #67 SMP Sat Jan 27
17:20:09 IST 2024
[ 0.000000] random: crng init done
[ 0.000000] Machine model: riscv-virtio,qemu
[ 0.000000] SBI specification v2.0 detected
[ 0.000000] SBI implementation ID=0x1 Version=0x10004
[ 0.000000] SBI TIME extension detected
[ 0.000000] SBI IPI extension detected
[ 0.000000] SBI RFENCE extension detected
[ 0.000000] SBI SRST extension detected
[ 0.000000] SBI DBCN extension detected
[ 0.000000] earlycon: ns16550a0 at MMIO 0x0000000010000000 (options '')
[ 0.000000] printk: legacy bootconsole [ns16550a0] enabled
[ 0.000000] efi: EFI v2.10 by Das U-Boot
[ 0.000000] efi: RTPROP=0x8df05040 SMBIOS=0x8df01000 RNG=0x8c972040
MEMRESERVE=0x8c971040
[ 0.000000] OF: reserved mem:
0x0000000080000000..0x000000008003ffff (256 KiB) nomap non-reusable
mmode_resv0@80000000
[ 0.000000] OF: reserved mem:
0x0000000080040000..0x000000008007ffff (256 KiB) nomap non-reusable
mmode_resv1@80040000
[ 0.000000] Zone ranges:
[ 0.000000] DMA32 [mem 0x0000000080000000-0x000000008fffffff]
[ 0.000000] Normal empty
[ 0.000000] Movable zone start for each node
[ 0.000000] Early memory node ranges
[ 0.000000] node 0: [mem 0x0000000080000000-0x000000008007ffff]
[ 0.000000] node 0: [mem 0x0000000080080000-0x000000008df00fff]
[ 0.000000] node 0: [mem 0x000000008df01000-0x000000008df01fff]
[ 0.000000] node 0: [mem 0x000000008df02000-0x000000008df04fff]
[ 0.000000] node 0: [mem 0x000000008df05000-0x000000008df05fff]
[ 0.000000] node 0: [mem 0x000000008df06000-0x000000008df06fff]
[ 0.000000] node 0: [mem 0x000000008df07000-0x000000008df08fff]
[ 0.000000] node 0: [mem 0x000000008df09000-0x000000008df09fff]
[ 0.000000] node 0: [mem 0x000000008df0a000-0x000000008df19fff]
[ 0.000000] node 0: [mem 0x000000008df1a000-0x000000008f741fff]
[ 0.000000] node 0: [mem 0x000000008f742000-0x000000008f742fff]
[ 0.000000] node 0: [mem 0x000000008f743000-0x000000008fffffff]
[ 0.000000] Initmem setup node 0 [mem 0x0000000080000000-0x000000008fffffff]
[ 0.000000] SBI HSM extension detected
[ 0.000000] Falling back to deprecated "riscv,isa"
[ 0.000000] riscv: base ISA extensions acdfhim
[ 0.000000] riscv: ELF capabilities acdfim
[ 0.000000] percpu: Embedded 20 pages/cpu s41464 r8192 d32264 u81920
[ 0.000000] Kernel command line: root=/dev/vda rootwait rw
console=ttyS0 earlycon
[ 0.000000] Dentry cache hash table entries: 32768 (order: 6,
262144 bytes, linear)
[ 0.000000] Inode-cache hash table entries: 16384 (order: 5, 131072
bytes, linear)
[ 0.000000] Built 1 zonelists, mobility grouping on. Total pages: 64512
[ 0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
[ 0.000000] Virtual kernel memory layout:
[ 0.000000] fixmap : 0xff1bfffffea00000 - 0xff1bffffff000000
(6144 kB)
[ 0.000000] pci io : 0xff1bffffff000000 - 0xff1c000000000000
( 16 MB)
[ 0.000000] vmemmap : 0xff1c000000000000 - 0xff20000000000000
(1024 TB)
[ 0.000000] vmalloc : 0xff20000000000000 - 0xff60000000000000
(16384 TB)
[ 0.000000] modules : 0xffffffff01582000 - 0xffffffff80000000
(2026 MB)
[ 0.000000] lowmem : 0xff60000000000000 - 0xff60000010000000
( 256 MB)
[ 0.000000] kernel : 0xffffffff80000000 - 0xffffffffffffffff
(2047 MB)
[ 0.000000] Memory: 217364K/262144K available (9190K kernel code,
4939K rwdata, 4096K rodata, 2252K init, 489K bss, 44780K reserved, 0K
cma-reserved)
[ 0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=8, Nodes=1
[ 0.000000] rcu: Hierarchical RCU implementation.
[ 0.000000] rcu: RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=8.
[ 0.000000] rcu: RCU debug extended QS entry/exit.
[ 0.000000] Tracing variant of Tasks RCU enabled.
[ 0.000000] rcu: RCU calculated value of scheduler-enlistment delay
is 25 jiffies.
[ 0.000000] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=8
[ 0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[ 0.000000] riscv-intc: 64 local interrupts mapped using AIA
[ 0.000000] riscv-imsic: imsics@28000000: providing IPIs using interrupt 1
[ 0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[ 0.000000] clocksource: riscv_clocksource: mask:
0xffffffffffffffff max_cycles: 0x24e6a1710, max_idle_ns: 440795202120
ns
[ 0.000087] sched_clock: 64 bits at 10MHz, resolution 100ns, wraps
every 4398046511100ns
[ 0.001406] riscv-timer: Timer interrupt in S-mode is available via
sstc extension
[ 0.007310] Console: colour dummy device 80x25
[ 0.014343] Calibrating delay loop (skipped), value calculated
using timer frequency.. 20.00 BogoMIPS (lpj=40000)
[ 0.018315] pid_max: default: 32768 minimum: 301
[ 0.020982] LSM: initializing lsm=capability,integrity
[ 0.023969] Mount-cache hash table entries: 512 (order: 0, 4096
bytes, linear)
[ 0.025231] Mountpoint-cache hash table entries: 512 (order: 0,
4096 bytes, linear)
[ 0.066845] RCU Tasks Trace: Setting shift to 3 and lim to 1
rcu_task_cb_adjust=1.
[ 0.068829] riscv: ELF compat mode supported
[ 0.069115] ASID allocator using 16 bits (65536 entries)
[ 0.080952] rcu: Hierarchical SRCU implementation.
[ 0.081712] rcu: Max phase no-delay instances is 1000.
[ 0.086381] Remapping and enabling EFI services.
[ 0.093736] smp: Bringing up secondary CPUs ...
[ 0.162264] smp: Brought up 1 node, 8 CPUs
[ 0.186107] devtmpfs: initialized
[ 0.199725] clocksource: jiffies: mask: 0xffffffff max_cycles:
0xffffffff, max_idle_ns: 7645041785100000 ns
[ 0.200634] futex hash table entries: 2048 (order: 5, 131072 bytes, linear)
[ 0.203482] pinctrl core: initialized pinctrl subsystem
[ 0.213664] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[ 0.218255] DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
[ 0.221185] DMA: preallocated 128 KiB GFP_KERNEL|GFP_DMA32 pool for
atomic allocations
[ 0.222099] audit: initializing netlink subsys (disabled)
[ 0.228028] audit: type=2000 audit(0.168:1): state=initialized
audit_enabled=0 res=1
[ 0.230906] cpuidle: using governor menu
[ 0.289647] cpu2: Ratio of byte access time to unaligned word
access is 7.20, unaligned accesses are fast
[ 0.289661] cpu3: Ratio of byte access time to unaligned word
access is 5.94, unaligned accesses are fast
[ 0.289652] cpu4: Ratio of byte access time to unaligned word
access is 7.13, unaligned accesses are fast
[ 0.289625] cpu6: Ratio of byte access time to unaligned word
access is 10.28, unaligned accesses are fast
[ 0.289615] cpu1: Ratio of byte access time to unaligned word
access is 8.04, unaligned accesses are fast
[ 0.290252] cpu5: Ratio of byte access time to unaligned word
access is 7.13, unaligned accesses are fast
[ 0.299499] cpu7: Ratio of byte access time to unaligned word
access is 6.58, unaligned accesses are fast
[ 0.326695] cpu0: Ratio of byte access time to unaligned word
access is 7.78, unaligned accesses are fast
[ 0.354371] HugeTLB: registered 2.00 MiB page size, pre-allocated 0 pages
[ 0.354767] HugeTLB: 28 KiB vmemmap can be freed for a 2.00 MiB page
[ 0.361699] ACPI: Interpreter disabled.
[ 0.363441] iommu: Default domain type: Translated
[ 0.364215] iommu: DMA domain TLB invalidation policy: strict mode
[ 0.368128] SCSI subsystem initialized
[ 0.371067] usbcore: registered new interface driver usbfs
[ 0.371912] usbcore: registered new interface driver hub
[ 0.372389] usbcore: registered new device driver usb
[ 0.375075] efivars: Registered efivars operations
[ 0.389652] vgaarb: loaded
[ 0.443368] clocksource: Switched to clocksource riscv_clocksource
[ 0.449125] pnp: PnP ACPI: disabled
[ 0.499449] NET: Registered PF_INET protocol family
[ 0.500979] IP idents hash table entries: 4096 (order: 3, 32768
bytes, linear)
[ 0.507062] tcp_listen_portaddr_hash hash table entries: 128
(order: 0, 4096 bytes, linear)
[ 0.507775] Table-perturb hash table entries: 65536 (order: 6,
262144 bytes, linear)
[ 0.508351] TCP established hash table entries: 2048 (order: 2,
16384 bytes, linear)
[ 0.508930] TCP bind hash table entries: 2048 (order: 5, 131072
bytes, linear)
[ 0.509942] TCP: Hash tables configured (established 2048 bind 2048)
[ 0.511459] UDP hash table entries: 256 (order: 2, 24576 bytes, linear)
[ 0.512262] UDP-Lite hash table entries: 256 (order: 2, 24576 bytes, linear)
[ 0.514937] NET: Registered PF_UNIX/PF_LOCAL protocol family
[ 0.521225] RPC: Registered named UNIX socket transport module.
[ 0.521913] RPC: Registered udp transport module.
[ 0.522324] RPC: Registered tcp transport module.
[ 0.522656] RPC: Registered tcp-with-tls transport module.
[ 0.523178] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.523787] PCI: CLS 0 bytes, default 64
[ 0.529358] workingset: timestamp_bits=46 max_order=16 bucket_order=0
[ 0.537946] NFS: Registering the id_resolver key type
[ 0.539478] Key type id_resolver registered
[ 0.539918] Key type id_legacy registered
[ 0.540656] nfs4filelayout_init: NFSv4 File Layout Driver Registering...
[ 0.542911] nfs4flexfilelayout_init: NFSv4 Flexfile Layout Driver
Registering...
[ 0.544894] 9p: Installing v9fs 9p2000 file system support
[ 0.548517] NET: Registered PF_ALG protocol family
[ 0.549459] Block layer SCSI generic (bsg) driver version 0.4
loaded (major 245)
[ 0.550658] io scheduler mq-deadline registered
[ 0.552112] io scheduler kyber registered
[ 0.552442] io scheduler bfq registered
[ 0.556517] riscv-imsic: imsics@28000000: hart-index-bits: 3,
guest-index-bits: 0
[ 0.556955] riscv-imsic: imsics@28000000: group-index-bits: 0,
group-index-shift: 24
[ 0.557403] riscv-imsic: imsics@28000000: per-CPU IDs 255 at base
PPN 0x0000000028000000
[ 0.557699] riscv-imsic: imsics@28000000: total 2032 interrupts available
[ 0.561962] pci-host-generic 30000000.pci: host bridge
/soc/pci@30000000 ranges:
[ 0.563422] pci-host-generic 30000000.pci: IO
0x0003000000..0x000300ffff -> 0x0000000000
[ 0.564475] pci-host-generic 30000000.pci: MEM
0x0040000000..0x007fffffff -> 0x0040000000
[ 0.565013] pci-host-generic 30000000.pci: MEM
0x0400000000..0x07ffffffff -> 0x0400000000
[ 0.566349] pci-host-generic 30000000.pci: Memory resource size
exceeds max for 32 bits
[ 0.567633] pci-host-generic 30000000.pci: ECAM at [mem
0x30000000-0x3fffffff] for [bus 00-ff]
[ 0.569300] pci-host-generic 30000000.pci: PCI host bridge to bus 0000:00
[ 0.570172] pci_bus 0000:00: root bus resource [bus 00-ff]
[ 0.570559] pci_bus 0000:00: root bus resource [io 0x0000-0xffff]
[ 0.570969] pci_bus 0000:00: root bus resource [mem 0x40000000-0x7fffffff]
[ 0.571595] pci_bus 0000:00: root bus resource [mem 0x400000000-0x7ffffffff]
[ 0.573646] pci 0000:00:00.0: [1b36:0008] type 00 class 0x060000
conventional PCI endpoint
[ 0.654069] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[ 0.659475] SuperH (H)SCI(F) driver initialized
[ 0.675004] loop: module loaded
[ 0.680024] e1000e: Intel(R) PRO/1000 Network Driver
[ 0.680162] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[ 0.684590] usbcore: registered new interface driver uas
[ 0.685245] usbcore: registered new interface driver usb-storage
[ 0.686530] mousedev: PS/2 mouse device common for all mice
[ 0.693125] syscon-poweroff poweroff: pm_power_off already claimed
for sbi_srst_power_off
[ 0.694774] syscon-poweroff: probe of poweroff failed with error -16
[ 0.698092] sdhci: Secure Digital Host Controller Interface driver
[ 0.698484] sdhci: Copyright(c) Pierre Ossman
[ 0.699333] Synopsys Designware Multimedia Card Interface Driver
[ 0.699869] sdhci-pltfm: SDHCI platform and OF driver helper
[ 0.700673] usbcore: registered new interface driver usbhid
[ 0.700920] usbhid: USB HID core driver
[ 0.701501] riscv-pmu-sbi: SBI PMU extension is available
[ 0.702263] riscv-pmu-sbi: 16 firmware and 18 hardware counters
[ 0.702618] riscv-pmu-sbi: Perf sampling/filtering is not supported
as sscof extension is not available
[ 0.709934] NET: Registered PF_INET6 protocol family
[ 0.723647] Segment Routing with IPv6
[ 0.724210] In-situ OAM (IOAM) with IPv6
[ 0.724882] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[ 0.727936] NET: Registered PF_PACKET protocol family
[ 0.729289] 9pnet: Installing 9P2000 support
[ 0.729796] Key type dns_resolver registered
[ 0.763394] debug_vm_pgtable: [debug_vm_pgtable ]:
Validating architecture page table helpers
[ 0.772054] riscv-aplic d000000.aplic: 96 interrupts forwared to
MSI base 0x0000000028000000
[ 0.775578] virtio_blk virtio0: 1/0/0 default/read/poll queues
[ 0.782792] virtio_blk virtio0: [vda] 65536 512-byte logical blocks
(33.6 MB/32.0 MiB)
[ 0.827635] printk: legacy console [ttyS0] disabled
[ 0.830784] 10000000.serial: ttyS0 at MMIO 0x10000000 (irq = 14,
base_baud = 230400) is a 16550A
[ 0.833076] printk: legacy console [ttyS0] enabled
[ 0.833076] printk: legacy console [ttyS0] enabled
[ 0.833856] printk: legacy bootconsole [ns16550a0] disabled
[ 0.833856] printk: legacy bootconsole [ns16550a0] disabled
[ 0.843499] goldfish_rtc 101000.rtc: registered as rtc0
[ 0.844980] goldfish_rtc 101000.rtc: setting system clock to
2024-01-30T10:19:33 UTC (1706609973)
[ 0.848495] clk: Disabling unused clocks
[ 0.884046] EXT4-fs (vda): warning: mounting unchecked fs, running
e2fsck is recommended
[ 0.891369] EXT4-fs (vda): mounted filesystem
00000000-0000-0000-0000-000000000000 r/w without journal. Quota mode:
disabled.
[ 0.892199] ext4 filesystem being mounted at /root supports
timestamps until 2038-01-19 (0x7fffffff)
[ 0.892644] VFS: Mounted root (ext4 filesystem) on device 254:0.
[ 0.895564] devtmpfs: mounted
[ 0.986847] Freeing unused kernel image (initmem) memory: 2252K
[ 0.988406] Run /sbin/init as init process
mount: mounting devtmpfs on /dev failed: Device or resource busy
_ _
| ||_|
| | _ ____ _ _ _ _
| || | _ \| | | |\ \/ /
| || | | | | |_| |/ \
|_||_|_| |_|\____|\_/\_/

Busybox Rootfs

Please press Enter to activate this console.
/ #
/ # cat /proc/interrupts
CPU0 CPU1 CPU2 CPU3 CPU4 CPU5
CPU6 CPU7
10: 103 116 58 214 96 47
78 52 RISC-V INTC 5 Edge riscv-timer
11: 0 44 0 0 0 0
0 0 APLIC-MSI-d000000.aplic 8 Level virtio0
12: 0 0 0 0 0 0
0 0 APLIC-MSI-d000000.aplic 7 Level virtio1
13: 0 0 0 6 0 0
0 0 APLIC-MSI-d000000.aplic 6 Level virtio2
14: 0 0 0 0 64 0
0 0 APLIC-MSI-d000000.aplic 10 Level ttyS0
15: 0 0 0 0 0 0
0 0 APLIC-MSI-d000000.aplic 11 Level
101000.rtc
IPI0: 4 9 12 6 5 10
13 7 Rescheduling interrupts
IPI1: 605 477 442 315 392 434
405 417 Function call interrupts
IPI2: 0 0 0 0 0 0
0 0 CPU stop interrupts
IPI3: 0 0 0 0 0 0
0 0 CPU stop (for crash dump) interrupts
IPI4: 0 0 0 0 0 0
0 0 IRQ work interrupts
IPI5: 0 0 0 0 0 0
0 0 Timer broadcast interrupts
/ #
/ #
/ # poweroff
/ # umount: devtmpfs busy - remounted read-only
[ 24.504316] EXT4-fs (vda): re-mounted
00000000-0000-0000-0000-000000000000 ro. Quota mode: disabled.
The system is going down NOW!
Sent SIGTERM to all processes
Sent SIGKILL to[ 26.543142] reboot: Power down


Regards,
Anup