rw我一直在摸不着头脑，为什么即使作为内核参数传递，qemu 也可能无法写入根？在 SDA 设备上，我有一个 EFI 分区（/dev/sda1）和 LUKS（/dev/sda2）加密分区（在执行 fdisk -l 时分区类型显示为未知，我认为这是正常的，因为它是加密的）。
这是我尝试运行它的方法：
qemu-system-x86_64 -enable-kvm -s -kernel arch/x86_64/boot/bzImage -boot c -m 512M -hda ../buildroot/output/images/rootfs.ext4 -append "root=/dev/sda rw console=ttyS0 acpi=off nokaslr" -serial stdio -display none
这里的输出：
[ 0.000000] Linux version 5.9.0-rc8-next-20201008 ([email protected]) (gcc (GCC) 9.3.0, GNU ld version 2.33.1-slack15) #1 SMP Thu Oct 8 15:12:53 CDT 2020
[ 0.000000] Command line: root=/dev/sda rw console=ttyS0 acpi=off nokaslr
[ 0.000000] x86/fpu: x87 FPU will use FXSAVE
[ 0.000000] BIOS-provided physical RAM map:
[ 0.000000] BIOS-e820: [mem 0x0000000000000000-0x000000000009fbff] usable
[ 0.000000] BIOS-e820: [mem 0x000000000009fc00-0x000000000009ffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000000f0000-0x00000000000fffff] reserved
[ 0.000000] BIOS-e820: [mem 0x0000000000100000-0x000000001ffdffff] usable
[ 0.000000] BIOS-e820: [mem 0x000000001ffe0000-0x000000001fffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000feffc000-0x00000000feffffff] reserved
[ 0.000000] BIOS-e820: [mem 0x00000000fffc0000-0x00000000ffffffff] reserved
[ 0.000000] NX (Execute Disable) protection: active
[ 0.000000] SMBIOS 2.8 present.
[ 0.000000] DMI: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 0.000000] tsc: Fast TSC calibration using PIT
[ 0.000000] tsc: Detected 2394.267 MHz processor
[ 0.000675] last_pfn = 0x1ffe0 max_arch_pfn = 0x400000000
[ 0.000715] x86/PAT: PAT not supported by the CPU.
[ 0.000720] x86/PAT: Configuration [0-7]: WB WT UC- UC WB WT UC- UC
[ 0.007649] found SMP MP-table at [mem 0x000f5b00-0x000f5b0f]
[ 0.007691] check: Scanning 1 areas for low memory corruption
[ 0.008035] No NUMA configuration found
[ 0.008036] Faking a node at [mem 0x0000000000000000-0x000000001ffdffff]
[ 0.008043] NODE_DATA(0) allocated [mem 0x1ffdc000-0x1ffdffff]
[ 0.008064] Zone ranges:
[ 0.008065] DMA [mem 0x0000000000001000-0x0000000000ffffff]
[ 0.008067] DMA32 [mem 0x0000000001000000-0x000000001ffdffff]
[ 0.008068] Normal empty
[ 0.008069] Movable zone start for each node
[ 0.008070] Early memory node ranges
[ 0.008071] node 0: [mem 0x0000000000001000-0x000000000009efff]
[ 0.008072] node 0: [mem 0x0000000000100000-0x000000001ffdffff]
[ 0.008436] Zeroed struct page in unavailable ranges: 130 pages
[ 0.008438] Initmem setup node 0 [mem 0x0000000000001000-0x000000001ffdffff]
[ 0.009962] Intel MultiProcessor Specification v1.4
[ 0.009966] MPTABLE: OEM ID: BOCHSCPU
[ 0.009967] MPTABLE: Product ID: 0.1
[ 0.009968] MPTABLE: APIC at: 0xFEE00000
[ 0.010001] Processor #0 (Bootup-CPU)
[ 0.010037] IOAPIC[0]: apic_id 0, version 17, address 0xfec00000, GSI 0-23
[ 0.010039] Processors: 1
[ 0.010044] smpboot: Allowing 1 CPUs, 0 hotplug CPUs
[ 0.010059] PM: hibernation: Registered nosave memory: [mem 0x00000000-0x00000fff]
[ 0.010060] PM: hibernation: Registered nosave memory: [mem 0x0009f000-0x0009ffff]
[ 0.010061] PM: hibernation: Registered nosave memory: [mem 0x000a0000-0x000effff]
[ 0.010062] PM: hibernation: Registered nosave memory: [mem 0x000f0000-0x000fffff]
[ 0.010064] [mem 0x20000000-0xfeffbfff] available for PCI devices
[ 0.010067] clocksource: refined-jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1910969940391419 ns
[ 0.014732] setup_percpu: NR_CPUS:64 nr_cpumask_bits:64 nr_cpu_ids:1 nr_node_ids:1
[ 0.015037] percpu: Embedded 52 pages/cpu s172888 r8192 d31912 u2097152
[ 0.015061] Built 1 zonelists, mobility grouping on. Total pages: 128873
[ 0.015062] Policy zone: DMA32
[ 0.015064] Kernel command line: root=/dev/sda rw console=ttyS0 acpi=off nokaslr
[ 0.015154] Dentry cache hash table entries: 65536 (order: 7, 524288 bytes, linear)
[ 0.015174] Inode-cache hash table entries: 32768 (order: 6, 262144 bytes, linear)
[ 0.015203] mem auto-init: stack:off, heap alloc:off, heap free:off
[ 0.016974] Memory: 483424K/523768K available (14350K kernel code, 2542K rwdata, 3460K rodata, 1184K init, 1892K bss, 40088K reserved, 0K cma-reserved)
[ 0.017014] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[ 0.017024] Kernel/User page tables isolation: enabled
[ 0.017335] rcu: Hierarchical RCU implementation.
[ 0.017336] rcu: RCU event tracing is enabled.
[ 0.017337] rcu: RCU restricting CPUs from NR_CPUS=64 to nr_cpu_ids=1.
[ 0.017339] rcu: RCU calculated value of scheduler-enlistment delay is 100 jiffies.
[ 0.017340] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=1
[ 0.018033] NR_IRQS: 4352, nr_irqs: 256, preallocated irqs: 16
[ 0.018273] random: get_random_bytes called from start_kernel+0x35e/0x529 with crng_init=0
[ 0.024128] Console: colour VGA+ 80x25
[ 0.220048] printk: console [ttyS0] enabled
[ 0.223417] APIC: Switch to symmetric I/O mode setup
[ 0.226862] ..TIMER: vector=0x30 apic1=0 pin1=2 apic2=-1 pin2=-1
[ 0.235353] clocksource: tsc-early: mask: 0xffffffffffffffff max_cycles: 0x22830ff24b8, max_idle_ns: 440795323111 ns
[ 0.240552] Calibrating delay loop (skipped), value calculated using timer frequency.. 4788.53 BogoMIPS (lpj=2394267)
[ 0.247543] pid_max: default: 32768 minimum: 301
[ 0.249678] LSM: Security Framework initializing
[ 0.252642] SELinux: Initializing.
[ 0.253560] Mount-cache hash table entries: 1024 (order: 1, 8192 bytes, linear)
[ 0.254531] Mountpoint-cache hash table entries: 1024 (order: 1, 8192 bytes, linear)
[ 0.255970] Last level iTLB entries: 4KB 0, 2MB 0, 4MB 0
[ 0.259540] Last level dTLB entries: 4KB 0, 2MB 0, 4MB 0, 1GB 0
[ 0.261588] Spectre V1 : Mitigation: usercopy/swapgs barriers and __user pointer sanitization
[ 0.265539] Spectre V2 : Mitigation: Full generic retpoline
[ 0.272537] Spectre V2 : Spectre v2 / SpectreRSB mitigation: Filling RSB on context switch
[ 0.278539] Speculative Store Bypass: Vulnerable
[ 0.280547] MDS: Vulnerable: Clear CPU buffers attempted, no microcode
[ 0.290942] Freeing SMP alternatives memory: 40K
[ 0.486531] random: fast init done
[ 0.500182] smpboot: CPU0: Intel QEMU Virtual CPU version 2.5+ (family: 0x6, model: 0x6, stepping: 0x3)
[ 0.500664] Performance Events: PMU not available due to virtualization, using software events only.
[ 0.502571] rcu: Hierarchical SRCU implementation.
[ 0.503829] smp: Bringing up secondary CPUs ...
[ 0.504555] smp: Brought up 1 node, 1 CPU
[ 0.505531] smpboot: Max logical packages: 1
[ 0.506547] smpboot: Total of 1 processors activated (4788.53 BogoMIPS)
[ 0.508802] devtmpfs: initialized
[ 0.511677] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 1911260446275000 ns
[ 0.512568] futex hash table entries: 256 (order: 2, 16384 bytes, linear)
[ 0.514182] PM: RTC time: 00:18:07, date: 2020-10-12
[ 0.514658] NET: Registered protocol family 16
[ 0.515673] audit: initializing netlink subsys (disabled)
[ 0.516701] thermal_sys: Registered thermal governor 'step_wise'
[ 0.516705] thermal_sys: Registered thermal governor 'user_space'
[ 0.517594] cpuidle: using governor menu
[ 0.519840] PCI: Using configuration type 1 for base access
[ 0.520556] audit: type=2000 audit(1602461887.286:1): state=initialized audit_enabled=0 res=1
[ 0.525088] HugeTLB registered 2.00 MiB page size, pre-allocated 0 pages
[ 0.526036] cryptomgr_test (19) used greatest stack depth: 15648 bytes left
[ 0.529047] ACPI: Interpreter disabled.
[ 0.529640] iommu: Default domain type: Translated
[ 0.530793] vgaarb: loaded
[ 0.532623] SCSI subsystem initialized
[ 0.533743] usbcore: registered new interface driver usbfs
[ 0.534658] usbcore: registered new interface driver hub
[ 0.535655] usbcore: registered new device driver usb
[ 0.536608] pps_core: LinuxPPS API ver. 1 registered
[ 0.537536] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <[email protected]>
[ 0.538597] PTP clock support registered
[ 0.539640] Advanced Linux Sound Architecture Driver Initialized.
[ 0.541133] NetLabel: Initializing
[ 0.541531] NetLabel: domain hash size = 128
[ 0.542542] NetLabel: protocols = UNLABELED CIPSOv4 CALIPSO
[ 0.543561] NetLabel: unlabeled traffic allowed by default
[ 0.544616] PCI: Probing PCI hardware
[ 0.545566] PCI host bridge to bus 0000:00
[ 0.546581] pci_bus 0000:00: root bus resource [io 0x0000-0xffff]
[ 0.547571] pci_bus 0000:00: root bus resource [mem 0x00000000-0xffffffffff]
[ 0.548649] pci_bus 0000:00: No busn resource found for root bus, will use [bus 00-ff]
[ 0.550684] pci 0000:00:00.0: [8086:1237] type 00 class 0x060000
[ 0.552794] pci 0000:00:01.0: [8086:7000] type 00 class 0x060100
[ 0.555026] pci 0000:00:01.1: [8086:7010] type 00 class 0x010180
[ 0.561550] pci 0000:00:01.1: reg 0x20: [io 0xc040-0xc04f]
[ 0.563636] pci 0000:00:01.1: legacy IDE quirk: reg 0x10: [io 0x01f0-0x01f7]
[ 0.564587] pci 0000:00:01.1: legacy IDE quirk: reg 0x14: [io 0x03f6]
[ 0.565543] pci 0000:00:01.1: legacy IDE quirk: reg 0x18: [io 0x0170-0x0177]
[ 0.566532] pci 0000:00:01.1: legacy IDE quirk: reg 0x1c: [io 0x0376]
[ 0.568543] pci 0000:00:01.3: [8086:7113] type 00 class 0x068000
[ 0.570982] pci 0000:00:01.3: quirk: [io 0x0600-0x063f] claimed by PIIX4 ACPI
[ 0.571579] pci 0000:00:01.3: quirk: [io 0x0700-0x070f] claimed by PIIX4 SMB
[ 0.572894] pci 0000:00:02.0: [1234:1111] type 00 class 0x030000
[ 0.575588] pci 0000:00:02.0: reg 0x10: [mem 0xfd000000-0xfdffffff pref]
[ 0.580558] pci 0000:00:02.0: reg 0x18: [mem 0xfebf0000-0xfebf0fff]
[ 0.587329] pci 0000:00:02.0: reg 0x30: [mem 0xfebe0000-0xfebeffff pref]
[ 0.587918] pci 0000:00:02.0: vgaarb: setting as boot VGA device
[ 0.588527] pci 0000:00:02.0: vgaarb: VGA device added: decodes=io+mem,owns=io+mem,locks=none
[ 0.588585] pci 0000:00:03.0: [8086:100e] type 00 class 0x020000
[ 0.590866] pci 0000:00:03.0: reg 0x10: [mem 0xfebc0000-0xfebdffff]
[ 0.592536] pci 0000:00:03.0: reg 0x14: [io 0xc000-0xc03f]
[ 0.601568] pci 0000:00:03.0: reg 0x30: [mem 0xfeb80000-0xfebbffff pref]
[ 0.603766] pci_bus 0000:00: busn_res: [bus 00-ff] end is updated to 00
[ 0.604708] pci 0000:00:01.0: PIIX/ICH IRQ router [8086:7000]
[ 0.606218] clocksource: Switched to clocksource tsc-early
[ 0.705718] VFS: Disk quotas dquot_6.6.0
[ 0.707856] VFS: Dquot-cache hash table entries: 512 (order 0, 4096 bytes)
[ 0.711281] pnp: PnP ACPI: disabled
[ 0.715822] NET: Registered protocol family 2
[ 0.716862] tcp_listen_portaddr_hash hash table entries: 256 (order: 0, 4096 bytes, linear)
[ 0.718271] TCP established hash table entries: 4096 (order: 3, 32768 bytes, linear)
[ 0.721745] TCP bind hash table entries: 4096 (order: 4, 65536 bytes, linear)
[ 0.723735] TCP: Hash tables configured (established 4096 bind 4096)
[ 0.728525] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.730514] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
[ 0.734861] NET: Registered protocol family 1
[ 0.738613] RPC: Registered named UNIX socket transport module.
[ 0.742290] RPC: Registered udp transport module.
[ 0.745538] RPC: Registered tcp transport module.
[ 0.748892] RPC: Registered tcp NFSv4.1 backchannel transport module.
[ 0.752057] pci_bus 0000:00: resource 4 [io 0x0000-0xffff]
[ 0.755532] pci_bus 0000:00: resource 5 [mem 0x00000000-0xffffffffff]
[ 0.760558] pci 0000:00:01.0: PIIX3: Enabling Passive Release
[ 0.763781] pci 0000:00:00.0: Limiting direct PCI/PCI transfers
[ 0.767628] pci 0000:00:01.0: Activating ISA DMA hang workarounds
[ 0.771898] pci 0000:00:02.0: Video device with shadowed ROM at [mem 0x000c0000-0x000dffff]
[ 0.777519] PCI: CLS 0 bytes, default 64
[ 0.780538] platform rtc_cmos: registered platform RTC device (no PNP device found)
[ 0.782407] check: Scanning for low memory corruption every 60 seconds
[ 0.784712] Initialise system trusted keyrings
[ 0.786256] workingset: timestamp_bits=56 max_order=17 bucket_order=0
[ 0.795398] NFS: Registering the id_resolver key type
[ 0.801489] Key type id_resolver registered
[ 0.803012] Key type id_legacy registered
[ 0.816532] Key type asymmetric registered
[ 0.817385] Asymmetric key parser 'x509' registered
[ 0.818266] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[ 0.820182] io scheduler mq-deadline registered
[ 0.823180] io scheduler kyber registered
[ 0.828207] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[ 0.832849] acpi_thermal_pm (49) used greatest stack depth: 15480 bytes left
[ 1.095190] serial8250: ttyS0 at I/O 0x3f8 (irq = 4, base_baud = 115200) is a 16550A
[ 1.097511] Non-volatile memory driver v1.3
[ 1.099943] Linux agpgart interface v0.103
[ 1.105713] loop: module loaded
[ 1.108460] scsi host0: ata_piix
[ 1.109983] scsi host1: ata_piix
[ 1.110355] ata1: PATA max MWDMA2 cmd 0x1f0 ctl 0x3f6 bmdma 0xc040 irq 14
[ 1.111065] ata2: PATA max MWDMA2 cmd 0x170 ctl 0x376 bmdma 0xc048 irq 15
[ 1.111888] e100: Intel(R) PRO/100 Network Driver
[ 1.112368] e100: Copyright(c) 1999-2006 Intel Corporation
[ 1.112958] e1000: Intel(R) PRO/1000 Network Driver
[ 1.113448] e1000: Copyright (c) 1999-2006 Intel Corporation.
[ 1.115785] e1000 0000:00:03.0: PCI->APIC IRQ transform: INT A -> IRQ 11
[ 1.269674] ata1.00: ATA-7: QEMU HARDDISK, 2.5+, max UDMA/100
[ 1.271705] ata1.00: 262144 sectors, multi 16: LBA48
[ 1.278417] ata2.00: ATAPI: QEMU DVD-ROM, 2.5+, max UDMA/100
[ 1.281809] scsi 0:0:0:0: Direct-Access ATA QEMU HARDDISK 2.5+ PQ: 0 ANSI: 5
[ 1.284968] scsi 0:0:0:0: Attached scsi generic sg0 type 0
[ 1.290892] sd 0:0:0:0: [sda] 262144 512-byte logical blocks: (134 MB/128 MiB)
[ 1.292859] sd 0:0:0:0: [sda] Write Protect is off
[ 1.295305] scsi 1:0:0:0: CD-ROM QEMU QEMU DVD-ROM 2.5+ PQ: 0 ANSI: 5
[ 1.298745] ata2.00: WARNING: zero len r/w req
[ 1.299731] ata2.00: WARNING: zero len r/w req
[ 1.303356] sr 1:0:0:0: [sr0] scsi3-mmc drive: 4x/4x cd/rw xa/form2 tray
[ 1.308492] cdrom: Uniform CD-ROM driver Revision: 3.20
[ 1.312947] sd 0:0:0:0: [sda] Write cache: enabled, read cache: enabled, doesn't support DPO or FUA
[ 1.329880] sd 0:0:0:0: [sda] Attached SCSI disk
[ 1.330802] ata2.00: WARNING: zero len r/w req
[ 1.334184] ata2.00: WARNING: zero len r/w req
[ 1.342175] sr 1:0:0:0: Attached scsi generic sg1 type 5
[ 1.491095] e1000 0000:00:03.0 eth0: (PCI:33MHz:32-bit) 52:54:00:12:34:56
[ 1.493540] e1000 0000:00:03.0 eth0: Intel(R) PRO/1000 Network Connection
[ 1.496822] e1000e: Intel(R) PRO/1000 Network Driver
[ 1.499980] e1000e: Copyright(c) 1999 - 2015 Intel Corporation.
[ 1.503350] sky2: driver version 1.30
[ 1.505538] ehci_hcd: USB 2.0 'Enhanced' Host Controller (EHCI) Driver
[ 1.509092] ehci-pci: EHCI PCI platform driver
[ 1.512254] ohci_hcd: USB 1.1 'Open' Host Controller (OHCI) Driver
[ 1.515890] ohci-pci: OHCI PCI platform driver
[ 1.518804] uhci_hcd: USB Universal Host Controller Interface driver
[ 1.520356] usbcore: registered new interface driver usblp
[ 1.522653] usbcore: registered new interface driver usb-storage
[ 1.527491] i8042: PNP: No PS/2 controller found.
[ 1.530396] i8042: Probing ports directly.
[ 1.533650] serio: i8042 KBD port at 0x60,0x64 irq 1
[ 1.537820] serio: i8042 AUX port at 0x60,0x64 irq 12
[ 1.540903] input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input0
[ 1.545898] rtc_cmos rtc_cmos: registered as rtc0
[ 1.548024] rtc_cmos rtc_cmos: alarms up to one day, 114 bytes nvram
[ 1.552509] device-mapper: ioctl: 4.43.0-ioctl (2020-10-01) initialised: [email protected]
[ 1.557034] intel_pstate: CPU model not supported
[ 1.559853] hid: raw HID events driver (C) Jiri Kosina
[ 1.564553] usbcore: registered new interface driver usbhid
[ 1.566542] usbhid: USB HID core driver
[ 1.569210] Initializing XFRM netlink socket
[ 1.574331] NET: Registered protocol family 10
[ 1.578602] Segment Routing with IPv6
[ 1.581633] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[ 1.585939] NET: Registered protocol family 17
[ 1.589780] Key type dns_resolver registered
[ 1.592823] IPI shorthand broadcast: enabled
[ 1.596055] sched_clock: Marking stable (1383642043, 212282516)->(1710127529, -114202970)
[ 1.601854] registered taskstats version 1
[ 1.604677] Loading compiled-in X.509 certificates
[ 1.608624] PM: Magic number: 8:194:304
[ 1.611332] tty tty33: hash matches
[ 1.613673] printk: console [netcon0] enabled
[ 1.616965] netconsole: network logging started
[ 1.620807] cfg80211: Loading compiled-in X.509 certificates for regulatory database
[ 1.626547] kworker/u2:1 (60) used greatest stack depth: 14728 bytes left
[ 1.632632] cfg80211: Loaded X.509 cert 'sforshee: 00b28ddf47aef9cea7'
[ 1.636677] platform regulatory.0: Direct firmware load for regulatory.db failed with error -2
[ 1.640263] ALSA device list:
[ 1.640598] No soundcards found.
[ 1.642141] cfg80211: failed to load regulatory.db
[ 1.924478] clocksource: timekeeping watchdog on CPU0: Marking clocksource 'tsc-early' as unstable because the skew is too large:
[ 1.928017] clocksource: 'refined-jiffies' wd_now: fffb7208 wd_last: fffb7018 mask: ffffffff
[ 1.932015] clocksource: 'tsc-early' cs_now: 1461a011f cs_last: f2ea079f mask: ffffffffffffffff
[ 1.934037] tsc: Marking TSC unstable due to clocksource watchdog
[ 1.937207] TSC found unstable after boot, most likely due to broken BIOS. Use 'tsc=unstable'.
[ 1.938408] sched_clock: Marking unstable (1724916165, 212282516)<-(2051401484, -114202970)
[ 1.941488] clocksource: Switched to clocksource refined-jiffies
[ 2.231377] input: ImExPS/2 Generic Explorer Mouse as /devices/platform/i8042/serio1/input/input2
[ 2.232531] md: Waiting for all devices to be available before autodetect
[ 2.233445] md: If you don't use raid, use raid=noautodetect
[ 2.234449] md: Autodetecting RAID arrays.
[ 2.235435] md: autorun ...
[ 2.235965] md: ... autorun DONE.
[ 2.240432] ata1.00: WARNING: zero len r/w req
[ 2.241477] ata1.00: WARNING: zero len r/w req
[ 2.242464] ata1.00: WARNING: zero len r/w req
[ 2.244458] ata1.00: WARNING: zero len r/w req
[ 2.245449] ata1.00: WARNING: zero len r/w req
[ 2.246450] ata1.00: WARNING: zero len r/w req
[ 2.247459] sd 0:0:0:0: [sda] tag#0 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=0s
[ 2.248437] sd 0:0:0:0: [sda] tag#0 CDB: Synchronize Cache(10) 35 00 00 00 00 00 00 00 00 00
[ 2.249437] blk_update_request: I/O error, dev sda, sector 2 op 0x1:(WRITE) flags 0x800 phys_seg 1 prio class 0
[ 2.250426] Buffer I/O error on dev sda, logical block 1, lost sync page write
[ 2.250471] EXT4-fs (sda): I/O error while writing superblock
[ 2.251495] EXT4-fs (sda): mount failed
[ 2.252787] VFS: Cannot open root device "sda" or unknown-block(8,0): error -5
[ 2.253457] Please append a correct "root=" boot option; here are the available partitions:
[ 2.254473] 0800 131072 sda
[ 2.254478] driver: sd
[ 2.257447] 0b00 1048575 sr0
[ 2.257449] driver: sr
[ 2.259450] Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,0)
[ 2.260425] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.9.0-rc8-next-20201008 #1
[ 2.260425] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.12.1-0-ga5cab58e9a3f-prebuilt.qemu.org 04/01/2014
[ 2.260425] Call Trace:
[ 2.260425] dump_stack+0x57/0x6a
[ 2.260425] panic+0xfd/0x2be
[ 2.260425] mount_block_root+0x196/0x21a
[ 2.260425] mount_root+0xec/0x10a
[ 2.260425] prepare_namespace+0x136/0x165
[ 2.260425] kernel_init_freeable+0x1cf/0x1da
[ 2.260425] ? rest_init+0xc0/0xc0
[ 2.260425] kernel_init+0x5/0x100
[ 2.260425] ret_from_fork+0x22/0x30
[ 2.260425] Kernel Offset: disabled
[ 2.260425] ---[ end Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(8,0) ]---
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