hitHuang opened a new pull request, #19438:
URL: https://github.com/apache/nuttx/pull/19438
## Summary
`host_flags_to_mode()` in `arch/arm64/src/common/arm64_hostfs.c`,
`arch/arm/src/common/arm_hostfs.c`, and
`arch/risc-v/src/common/riscv_hostfs.c`
(identical code in all three) used a trailing `0` entry in `modeflags[]` as
the
loop-termination sentinel when translating a POSIX `open()` flags value to
the ARM
semihosting `SYS_OPEN` mode index.
`O_RDONLY` is defined as `0` and is exactly `modeflags[1]`. Since the loop
terminated
as soon as it saw a `0` entry, it stopped one iteration too early and never
got to
compare that entry, so a bare `O_RDONLY` open always fell through to
`-EINVAL`.
This breaks every semihosting-hostfs `open()` done with plain `O_RDONLY` —
which is
exactly what the ELF loader (`libelf_initialize()`) uses to open
executables. Any
`knsh`-style config that boots an init binary via semihosting hostfs hits a
fatal
`DEBUGASSERT(ret > 0)` in `sched/init/nx_bringup.c` right after
`load_absmodule: Loading /system/bin/init`, on every boot.
Fixed by bounding the loop by array size (`nitems()`) instead of a value
sentinel,
and dropping the now-unneeded trailing `0` entry.
## Impact
- Affects any board using `CONFIG_{ARM,ARM64,RISCV}_SEMIHOSTING_HOSTFS` to
open a file
with a bare `O_RDONLY` flag (no `O_TEXT`/`O_CREAT`/etc), most notably ELF
binfmt
loading a program from a semihosting-mounted hostfs.
- No Kconfig, API, or build system changes. Pure bugfix, no behavior change
for any
other flag combination.
## Testing
Verified on QEMU across all three affected architectures.
### rv-virt:knsh (default config)
Before fix — boot hangs with a fatal assertion:
```
ABC[ 0.032000] dump_assert_info: Current Version: NuttX 13.0.0
20579ab531-dirty Jul 15 2026 09:46:15 risc-v
[ 0.032000] dump_assert_info: Assertion failed : at file:
init/nx_bringup.c:389 task: AppBringUp process: Kernel 0x80201d04
[ 0.032000] up_dump_register: EPC: 80214720
[ 0.032000] up_dump_register: A0: 80607860 A1: 00000000 A2: 00000000 A3:
0000007e
[ 0.032000] up_dump_register: A4: 00000002 A5: 00000008 A6: 0000002e A7:
00000001
[ 0.032000] up_dump_register: T0: 00000000 T1: 00000000 T2: 00000000 T3:
00000000
[ 0.032000] up_dump_register: T4: 00000000 T5: 00000000 T6: 00000000
[ 0.032000] up_dump_register: S0: fffffffb S1: 00000000 S2: 8021b5ac S3:
00042022
[ 0.032000] up_dump_register: S4: 80608000 S5: 80608000 S6: 80608000 S7:
00000006
[ 0.032000] up_dump_register: S8: 00000185 S9: 80608e10 S10: 00000000
S11: 00000000
[ 0.032000] up_dump_register: SP: 8060c6b0 FP: fffffffb TP: 00000000 RA:
80214720
[ 0.032000] dump_stackinfo: User Stack:
[ 0.032000] dump_stackinfo: base: 0x8060c040
[ 0.032000] dump_stackinfo: size: 00001984
[ 0.032000] dump_stackinfo: sp: 0x8060c6b0
[ 0.032000] stack_dump: 0x8060c690: 80608e10 00000000 8021dff4 00042022
80606000 8021c5f4 8060c6b0 80214908
[ 0.032000] stack_dump: 0x8060c6b0: 80201d04 00000000 00000000 00000000
00000000 00000000 00000000 00000000
[ 0.032000] stack_dump: 0x8060c6d0: 00000000 00000000 80608e10 80607860
00000000 8021b5ac 00000185 7474754e
[ 0.032000] stack_dump: 0x8060c6f0: 00000058 00000000 00000000 00000000
00000000 00000000 00000000 00000000
[ 0.032000] stack_dump: 0x8060c710: 00000000 00000000 00000000 00000000
2e333100 00302e30 fffffffb 00000000
[ 0.032000] stack_dump: 0x8060c730: 00000000 30320000 61393735 31333562
7269642d 4a207974 31206c75 30322035
[ 0.032000] stack_dump: 0x8060c750: 30203632 36343a39 0035313a 8020990a
00000000 00000000 73697200 00762d63
[ 0.032000] stack_dump: 0x8060c770: 8060c7d0 80609078 fffffffb 802139f4
00000000 00000000 00000000 00000000
[ 0.032000] stack_dump: 0x8060c790: 00000000 00000000 00000000 00000000
00000000 00000064 fffffffb 8020785c
[ 0.032000] stack_dump: 0x8060c7b0: 00000000 00000064 00000c00 80201d64
00000000 00000000 00000000 00000000
[ 0.032000] stack_dump: 0x8060c7d0: 00026400 00000000 00000000 00000c00
00000000 80608e10 00000002 80202820
[ 0.032000] stack_dump: 0x8060c7f0: 00000000 00000000 00000000 00000000
00000000 00000000 00000000 00000000
[ 0.032000] dump_tasks: PID GROUP PRI POLICY TYPE NPX STATE
EVENT SIGMASK STACKBASE STACKSIZE COMMAND
[ 0.032000] dump_tasks: ---- --- --- -------- ------- --- -------
---------- ---------------- 0x80606000 2048 irq
[ 0.032000] dump_task: 0 0 0 FIFO Kthread - Ready
0000000000000000 0x80607b40 3040 Idle_Task
[ 0.032000] dump_task: 1 0 100 RR Kthread - Ready
0000000000000000 0x8060a050 1968 lpwork 0x80600010 0x80600060
[ 0.032000] dump_task: 2 0 240 RR Kthread - Running
0000000000000000 0x8060c040 1984 AppBringUp
```
Same failure reproduced on `qemu-armv7a:knsh` and `qemu-armv8a:knsh`.
After fix — boots cleanly to NSH:
```
ABC
NuttShell (NSH) NuttX-13.0.0
nsh>
nsh> ps
TID PID PPID PRI POLICY TYPE NPX STATE EVENT SIGMASK
STACK COMMAND
0 0 0 0 FIFO Kthread - Ready
0000000000000000 0003040 Idle_Task
1 0 0 100 RR Kthread - Waiting Semaphore
0000000000000000 0001968 lpwork 0x80600010 0x80600060
3 3 0 100 RR Task - Running
0000000000000000 0003008 /system/bin/init
nsh> uname -a
NuttX 13.0.0 e4c66d6c4f-dirty Jul 15 2026 09:50:54 risc-v rv-virt
```
Confirmed the same fix resolves boot on `qemu-armv7a:knsh` and
`qemu-armv8a:knsh` as well.
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