Constant SYS_SILO_PLEDGE 

pub const SYS_SILO_PLEDGE: usize = 809;

Restrict syscalls available to a silo (pledge).

• promises_ptr: pointer to the octal mode value string
• promises_len: length of the string

The new mode must be a subset of the current mode (monotonic restriction). Once pledged, the silo cannot gain additional capabilities.