It doesn't even specify which "invalid syscall".
```
$ src/bitcoind -sandbox=log-and-abort
2022-02-17T13:45:57Z Bitcoin Core version v22.99.0-b223c3c21e89 (release build)
2022-02-17T13:45:57Z Assuming ancestors of block 00000000000000000008a89e854d57e5667df88f1cdef6fde2fbca1de5b639ad have valid signatures.
2022-02-17T13:45:57Z Setting nMinimumChainWork=00000000000000000000000000000000000000001fa4663bbbe19f82de910280
2022-02-17T13:45:57Z Experimental syscall sandbox enabled (-sandbox=log-and-abort): bitcoind will terminate if an unexpected (not allowlisted) syscall is invoked.
2022-02-17T13:45:57Z Using the 'sse4(1way),sse41(4way),avx2(8way)' SHA256 implementation
2022-02-17T13:45:57Z Default data directory /…/.bitcoin
2022-02-17T13:45:57Z Using data directory /…/.bitcoin
2022-02-17T13:45:57Z Config file: /…/.bitcoin/bitcoin.conf (not found, skipping)
2022-02-17T13:45:57Z Command-line arg: sandbox="log-and-abort"
2022-02-17T13:45:57Z Using at most 125 automatic connections (1024 file descriptors available)
2022-02-17T13:45:57Z Using 16 MiB out of 32/2 requested for signature cache, able to store 524288 elements
2022-02-17T13:45:57Z Using 16 MiB out of 32/2 requested for script execution cache, able to store 524288 elements
2022-02-17T13:45:57Z Script verification uses 1 additional threads
Bad system call (core dumped)
```
Nothing in `dmesg` either.
{__NR_rt_sigreturn, "rt_sigreturn"},
    {__NR_rt_sigsuspend, "rt_sigsuspend"},
    {__NR_rt_sigtimedwait, "rt_sigtimedwait"},
    {__NR_rt_tgsigqueueinfo, "rt_tgsigqueueinfo"},
    {__NR_sched_get_priority_max, "sched_get_priority_max"},
    {__NR_sched_get_priority_min, "sched_get_priority_min"},
    {__NR_sched_getaffinity, "sched_getaffinity"},
    {__NR_sched_getattr, "sched_getattr"},
    {__NR_sched_getparam, "sched_getparam"},
    {__NR_sched_getscheduler, "sched_getscheduler"},
    {__NR_sched_rr_get_interval, "sched_rr_get_interval"},
    {__NR_sched_setaffinity, "sched_setaffinity"},
    {__NR_sched_setattr, "sched_setattr"},
    {__NR_sched_setparam, "sched_setparam"},
    {__NR_sched_setscheduler, "sched_setscheduler"},
    {__NR_sched_yield, "sched_yield"},
    {__NR_seccomp, "seccomp"},
    {__NR_security, "security"},
    {__NR_select, "select"},
    {__NR_semctl, "semctl"},
    {__NR_semget, "semget"},
    {__NR_semop, "semop"},
    {__NR_semtimedop, "semtimedop"},
    {__NR_sendfile, "sendfile"},
    {__NR_sendmmsg, "sendmmsg"},
    {__NR_sendmsg, "sendmsg"},
    {__NR_sendto, "sendto"},
    {__NR_set_mempolicy, "set_mempolicy"},
    {__NR_set_robust_list, "set_robust_list"},
    {__NR_set_thread_area, "set_thread_area"},