Simulation hangs indefinitely with generated Linux binary

[GMXX]

Following the instructions presented on the README, I've generated a custom Linux binary with USB support. The buildroot configuration file used is the default litex_vexriscv_usbhost_defconfig with the addition of the micropython package by uncommenting the line as follows:

# Extra packages
#BR2_PACKAGE_DHRYSTONE_OPT=y
BR2_PACKAGE_MICROPYTHON=y
#BR2_PACKAGE_SPIDEV_TEST=y
#BR2_PACKAGE_MTD=y
#BR2_PACKAGE_MTD_JFFS_UTILS=y

After the generation, I ran sim.py, but it hung at

Run /init as init process

Below is the complete simulation log:

        __   _ __      _  __
       / /  (_) /____ | |/_/
      / /__/ / __/ -_)>  <
     /____/_/\__/\__/_/|_|
   Build your hardware, easily!


 (c) Copyright 2012-2024 Enjoy-Digital
 (c) Copyright 2007-2015 M-Labs


 BIOS built on Sep 29 2024 20:37:58
 BIOS CRC passed (80d30a52)


 LiteX git sha1: 87ee6ec3a


--=============== SoC ==================--
CPU:		VexRiscv SMP-LINUX @ 100MHz
BUS:		wishbone 32-bit @ 4GiB
CSR:		32-bit data
ROM:		64.0KiB
SRAM:		8.0KiB
SDRAM:		64.0MiB 32-bit @ 100MT/s (CL-2 CWL-2)
MAIN-RAM:	64.0MiB


--========== Initialization ============--


Initializing SDRAM @0x40000000...
Switching SDRAM to software control.
Switching SDRAM to hardware control.


--============== Boot ==================--
Booting from serial...
Press Q or ESC to abort boot completely.
sL5DdSMmkekro
Timeout
Executing booted program at 0x40f00000


--============= Liftoff! ===============--


OpenSBI v1.3
   ____                    _____ ____ _____
  / __ \                  / ____|  _ \_   _|
 | |  | |_ __   ___ _ __ | (___ | |_) || |
 | |  | | '_ \ / _ \ '_ \ \___ \|  _ < | |
 | |__| | |_) |  __/ | | |____) | |_) || |_
  \____/| .__/ \___|_| |_|_____/|____/_____|
        | |
        |_|


Platform Name             : LiteX / VexRiscv-SMP
Platform Features         : medeleg
Platform HART Count       : 8
Platform IPI Device       : aclint-mswi
Platform Timer Device     : aclint-mtimer @ 100000000Hz
Platform Console Device   : litex_uart
Platform HSM Device       : ---
Platform PMU Device       : ---
Platform Reboot Device    : ---
Platform Shutdown Device  : ---
Platform Suspend Device   : ---
Platform CPPC Device      : ---
Firmware Base             : 0x40f00000
Firmware Size             : 376 KB
Firmware RW Offset        : 0x40000
Firmware RW Size          : 120 KB
Firmware Heap Offset      : 0x52000
Firmware Heap Size        : 48 KB (total), 3 KB (reserved), 8 KB (used), 36 KB (free)
Firmware Scratch Size     : 4096 B (total), 452 B (used), 3644 B (free)
Runtime SBI Version       : 1.0


Domain0 Name              : root
Domain0 Boot HART         : 0
Domain0 HARTs             : 0*,1*,2*,3*,4*,5*,6*,7*
Domain0 Region00          : 0xf0018000-0xf001bfff M: (I,R,W) S/U: ()
Domain0 Region01          : 0xf0010000-0xf0017fff M: (I,R,W) S/U: ()
Domain0 Region02          : 0x40f40000-0x40f5ffff M: (R,W) S/U: ()
Domain0 Region03          : 0x40f00000-0x40f3ffff M: (R,X) S/U: ()
Domain0 Region04          : 0x00000000-0xffffffff M: (R,W,X) S/U: (R,W,X)
Domain0 Next Address      : 0x40000000
Domain0 Next Arg1         : 0x40ef0000
Domain0 Next Mode         : S-mode
Domain0 SysReset          : yes
Domain0 SysSuspend        : yes


Boot HART ID              : 0
Boot HART Domain          : root
Boot HART Priv Version    : unknown
Boot HART Base ISA        : rv32ima
Boot HART ISA Extensions  : zicntr
Boot HART PMP Count       : 0
Boot HART PMP Granularity : 0
Boot HART PMP Address Bits: 0
Boot HART MHPM Count      : 0
Boot HART MIDELEG         : 0x00000222
Boot HART MEDELEG         : 0x0000b109
[    0.000000] Linux version 6.9.0 (stark@eOS) (riscv32-buildroot-linux-gnu-gcc.br_real (Buildroot 2024.08-761-g09964bc5c0) 13.3.0, GNU ld (GNU Binutils) 2.42) #1 SMP Sun Sep 29 20:28:22 -03 2024
[    0.000000] Machine model: sim
[    0.000000] SBI specification v1.0 detected
[    0.000000] SBI implementation ID=0x1 Version=0x10003
[    0.000000] SBI TIME extension detected
[    0.000000] SBI IPI extension detected
[    0.000000] SBI RFENCE extension detected
[    0.000000] earlycon: liteuart0 at I/O port 0x0 (options '')
[    0.000000] Malformed early option 'console'
[    0.000000] earlycon: liteuart0 at MMIO 0xf0001000 (options '')
[    0.000000] printk: legacy bootconsole [liteuart0] enabled
[    0.000000] OF: reserved mem: OVERLAP DETECTED!
[    0.000000] mmode_resv1@40f00000 (0x40f00000--0x40f40000) overlaps with opensbi@40f00000 (0x40f00000--0x40f80000)
[    0.000000] OF: reserved mem: OVERLAP DETECTED!
[    0.000000] opensbi@40f00000 (0x40f00000--0x40f80000) overlaps with mmode_resv0@40f40000 (0x40f40000--0x40f60000)
[    0.000000] OF: reserved mem: 0x40f00000..0x40f3ffff (256 KiB) nomap non-reusable mmode_resv1@40f00000
[    0.000000] OF: reserved mem: 0x40f00000..0x40f7ffff (512 KiB) map non-reusable opensbi@40f00000
[    0.000000] OF: reserved mem: 0x40f40000..0x40f5ffff (128 KiB) nomap non-reusable mmode_resv0@40f40000
[    0.000000] Zone ranges:
[    0.000000]   Normal   [mem 0x0000000040000000-0x0000000043ffffff]
[    0.000000] Movable zone start for each node
[    0.000000] Early memory node ranges
[    0.000000]   node   0: [mem 0x0000000040000000-0x0000000040efffff]
[    0.000000]   node   0: [mem 0x0000000040f00000-0x0000000040f5ffff]
[    0.000000]   node   0: [mem 0x0000000040f60000-0x0000000043ffffff]
[    0.000000] Initmem setup node 0 [mem 0x0000000040000000-0x0000000043ffffff]
[    0.000000] SBI HSM extension detected
[    0.000000] riscv: base ISA extensions aim
[    0.000000] riscv: ELF capabilities aim
[    0.000000] percpu: Embedded 11 pages/cpu s23188 r0 d21868 u45056
[    0.000000] Kernel command line: console=liteuart earlycon=liteuart,0xf0001000 rootwait root=/dev/ram0
[    0.000000] Dentry cache hash table entries: 8192 (order: 3, 32768 bytes, linear)
[    0.000000] Inode-cache hash table entries: 4096 (order: 2, 16384 bytes, linear)
[    0.000000] Built 1 zonelists, mobility grouping on.  Total pages: 16256
[    0.000000] mem auto-init: stack:all(zero), heap alloc:off, heap free:off
[    0.000000] Memory: 46256K/65536K available (7488K kernel code, 599K rwdata, 1264K rodata, 271K init, 257K bss, 19280K reserved, 0K cma-reserved)
[    0.000000] SLUB: HWalign=64, Order=0-3, MinObjects=0, CPUs=1, Nodes=1
[    0.000000] rcu: Hierarchical RCU implementation.
[    0.000000] rcu: 	RCU restricting CPUs from NR_CPUS=32 to nr_cpu_ids=1.
[    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=1
[    0.000000] NR_IRQS: 64, nr_irqs: 64, preallocated irqs: 0
[    0.000000] riscv-intc: 32 local interrupts mapped
[    0.000000] riscv: providing IPIs using SBI IPI extension
[    0.000000] rcu: srcu_init: Setting srcu_struct sizes based on contention.
[    0.000000] clocksource: riscv_clocksource: mask: 0xffffffffffffffff max_cycles: 0x171024e7e0, max_idle_ns: 440795205315 ns
[    0.000026] sched_clock: 64 bits at 100MHz, resolution 10ns, wraps every 4398046511100ns
[    0.003093] Console: colour dummy device 80x25
[    0.004118] Calibrating delay loop (skipped), value calculated using timer frequency.. 200.00 BogoMIPS (lpj=400000)
[    0.005042] pid_max: default: 32768 minimum: 301
[    0.009969] Mount-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.010732] Mountpoint-cache hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.053466] ASID allocator using 9 bits (512 entries)
[    0.058268] rcu: Hierarchical SRCU implementation.
[    0.058732] rcu: 	Max phase no-delay instances is 1000.
[    0.076128] smp: Bringing up secondary CPUs ...
[    0.076784] smp: Brought up 1 node, 1 CPU
[    0.088065] devtmpfs: initialized
[    0.135744] clocksource: jiffies: mask: 0xffffffff max_cycles: 0xffffffff, max_idle_ns: 7645041785100000 ns
[    0.137005] futex hash table entries: 256 (order: 2, 16384 bytes, linear)
[    0.176482] NET: Registered PF_NETLINK/PF_ROUTE protocol family
[    0.189512] DMA: preallocated 128 KiB GFP_KERNEL pool for atomic allocations
[    0.306677] cpu0: Ratio of byte access time to unaligned word access is 0.00, unaligned accesses are slow
[    0.323078] platform soc: Fixed dependency cycle(s) with /soc/interrupt-controller@f0c00000
[    0.333364] platform soc: Fixed dependency cycle(s) with /soc/interrupt-controller@f0c00000
[    0.377999] SCSI subsystem initialized
[    0.381391] usbcore: registered new interface driver usbfs
[    0.383013] usbcore: registered new interface driver hub
[    0.385070] usbcore: registered new device driver usb
[    0.389666] pps_core: LinuxPPS API ver. 1 registered
[    0.390167] pps_core: Software ver. 5.3.6 - Copyright 2005-2007 Rodolfo Giometti <giometti@linux.it>
[    0.391269] PTP clock support registered
[    0.397298] FPGA manager framework
[    0.399441] Advanced Linux Sound Architecture Driver Initialized.
[    0.420805] clocksource: Switched to clocksource riscv_clocksource
[    0.773200] NET: Registered PF_INET protocol family
[    0.778442] IP idents hash table entries: 2048 (order: 2, 16384 bytes, linear)
[    0.790937] tcp_listen_portaddr_hash hash table entries: 512 (order: 0, 4096 bytes, linear)
[    0.791812] Table-perturb hash table entries: 65536 (order: 6, 262144 bytes, linear)
[    0.793207] TCP established hash table entries: 1024 (order: 0, 4096 bytes, linear)
[    0.794172] TCP bind hash table entries: 1024 (order: 2, 16384 bytes, linear)
[    0.795174] TCP: Hash tables configured (established 1024 bind 1024)
[    0.797071] UDP hash table entries: 256 (order: 1, 8192 bytes, linear)
[    0.798007] UDP-Lite hash table entries: 256 (order: 1, 8192 bytes, linear)
[    0.829863] Unpacking initramfs...
[    0.839110] workingset: timestamp_bits=30 max_order=14 bucket_order=0
[    0.850256] Block layer SCSI generic (bsg) driver version 0.4 loaded (major 251)
[    0.850861] io scheduler mq-deadline registered
[    0.851382] io scheduler kyber registered
[    0.852290] io scheduler bfq registered
[    0.877329] riscv-plic f0c00000.interrupt-controller: mapped 32 interrupts with 1 handlers for 2 contexts.
[    0.895044] LiteX SoC Controller driver initialized
[    3.403317] Freeing initrd memory: 8192K
[    4.435874] f0001000.serial: ttyLXU0 at MMIO 0x0 (irq = 12, base_baud = 0) is a liteuart
[    4.437410] printk: legacy console [liteuart0] enabled
[    4.437410] printk: legacy console [liteuart0] enabled
[    4.438273] printk: legacy bootconsole [liteuart0] disabled
[    4.438273] printk: legacy bootconsole [liteuart0] disabled
[    4.474898] usbcore: registered new interface driver usb-storage
[    4.478156] usbcore: registered new interface driver ftdi_sio
[    4.479597] usbserial: USB Serial support registered for FTDI USB Serial Device
[    4.482938] UDC core: g_audio: couldn't find an available UDC
[    4.494943] mousedev: PS/2 mouse device common for all mice
[    4.499015] i2c_dev: i2c /dev entries driver
[    4.526705] usbcore: registered new interface driver usbhid
[    4.527306] usbhid: USB HID core driver
[    4.538164] usbcore: registered new interface driver snd-usb-audio
[    4.545997] NET: Registered PF_INET6 protocol family
[    4.571587] Segment Routing with IPv6
[    4.574311] In-situ OAM (IOAM) with IPv6
[    4.576898] sit: IPv6, IPv4 and MPLS over IPv4 tunneling driver
[    4.595487] NET: Registered PF_PACKET protocol family
[    5.147893] clk: Disabling unused clocks
[    5.149155] ALSA device list:
[    5.149634]   No soundcards found.
[    5.162803] Freeing unused kernel image (initmem) memory: 268K
[    5.163429] Kernel memory protection not selected by kernel config.
[    5.164185] Run /init as init process

[Rajnesh28]

How long did you wait after the last line printed before declaring the simulation as dead? Waiting for the busy box output to come alive after [...] Run /init as init process] can take a while in simulation.

I have never used the litex_vexriscv_usbhost_defconfig configuration for the Image (I have never looked into what it was even really for), but I have had success with litex_vexriscv_defconfig in both hardware and simulation in-case you're interested in trying that instead.

[enjoy-digital]

Thanks for the report. This was likely caused by the simulation DTB still using the old fixed 8 MiB initrd range, while a generated rootfs with USB host support and extra packages can be larger than that.

This is now addressed in 56df4f1: sim.py passes images/rootfs.cpio to the DTS generator when available, so linux,initrd-end is computed from the actual rootfs size instead of assuming 8 MiB.

Please retry with current master and regenerated simulation images. If there is still a hang after that, please share the updated boot log and the size of images/rootfs.cpio.