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_getitimer, "getitimer"},
    {__NR_getpeername, "getpeername"},
    {__NR_getpgid, "getpgid"},
    {__NR_getpgrp, "getpgrp"},
    {__NR_getpid, "getpid"},
    {__NR_getpmsg, "getpmsg"},
    {__NR_getppid, "getppid"},
    {__NR_getpriority, "getpriority"},
    {__NR_getrandom, "getrandom"},
    {__NR_getresgid, "getresgid"},
    {__NR_getresuid, "getresuid"},
    {__NR_getrlimit, "getrlimit"},
    {__NR_getrusage, "getrusage"},
    {__NR_getsid, "getsid"},
    {__NR_getsockname, "getsockname"},
    {__NR_getsockopt, "getsockopt"},
    {__NR_gettid, "gettid"},
    {__NR_gettimeofday, "gettimeofday"},
    {__NR_getuid, "getuid"},
    {__NR_getxattr, "getxattr"},
    {__NR_init_module, "init_module"},
    {__NR_inotify_add_watch, "inotify_add_watch"},
    {__NR_inotify_init, "inotify_init"},
    {__NR_inotify_init1, "inotify_init1"},
    {__NR_inotify_rm_watch, "inotify_rm_watch"},
    {__NR_io_cancel, "io_cancel"},
    {__NR_io_destroy, "io_destroy"},
    {__NR_io_getevents, "io_getevents"},
    {__NR_io_setup, "io_setup"},
    {__NR_io_submit, "io_submit"},