Actually we used this not long ago, so it's not new, even though it's not in the "official" list.  I think the whole syscall emulation area is big enough that it deserves its own keyword, and in fact there have been several variations over the years (see below).  However, it would be good to be more consistent.  I think we should pick one and put it on the list; any preference which?  I'd be OK with 'syscall emulation' or 'syscall emul'.  Plain 'syscall' seems a little too brief/ambiguous to me; I'd prefer 'syscall_emul' or 'sysemul' if we really want to keep them to one word.  'sycalls' is right out :).

% hg log | egrep -i '^summary:.*(sys?call|emul).*:'
summary:     syscall emulation: fix fast build issue
summary:     syscall emulation: fix DPRINTF arg ordering bug
summary:     syscall emulation: clean up & comment SyscallReturn
summary:     sysemul: bump all linux versions of for syscal emulation to 3.0.
summary:     syscall emulation: Enabled getrlimit and getrusage for x86.
summary:     syscall_emul: clean up open() code a bit.
summary:     syscall emulation: Clean up ioctl handling, and implement for x86.
summary:     syscall emulation: Add the futex system call.
summary:     Syscalls: warn when the length argument to mmap is excessive.
summary:     syscall_emul: implement MAP_FIXED option to mmap()
summary:     Syscall: Make the syscall function available in both SE and FS modes.
summary:     syscall emul: fix Power Linux mmap constant, plus other cleanup
summary:     Syscall: Don't close the simulator's standard file descriptors.
summary:     syscall: missing initializer in getcwd call
summary:     SysCalls: Implement truncate64 system call
summary:     Syscalls: Fix a warning turned error about an unused variable in m5.fast.
summary:     Syscalls: Make system calls access arguments like a stack, not an array.
summary:     syscall: Addition of an ioctl command code for Power.
summary:     syscall: Zero out memory that already exists during the brk system call.
summary:     syscall: Fix conversion of the stat64 buffer during system calls.
summary:     syscall: Implementation of the ftruncate64 system call.
summary:     syscall: Implementation of the time system call.
summary:     syscall: Implementation of the times system call
summary:     Syscalls: Implement sysinfo() syscall.
summary:     syscall_emul: style fixes (mostly wrapping overly long lines)
summary:     syscall: Resolve conflicts between m5threads and Gabe's recent SE changes.
summary:     mips-syscall: mark with correct flag. \nMIPS was using wrong serialization flag on syscall instructions allowing O3 to handle SE mode syscalls incorrectly and speculate on instructions after a syscall
summary:     sycalls: implement mremap() and add DATA flag for getrlimit(). mremap has been tested on Alpha, compiles for the rest but not tested. I don't see why it wouldn't work though.
summary:     syscall: Expose ioctl for MIPS
summary:     syscalls: fix latent brk/obreak bug.
summary:     syscall: Avoid a compiler warning which turns into a bug.
summary:     syscall: Fix TTY emulation in fstat() user-mode simulation for fd 1 (stdout).
summary:     syscalls: Add a bunch of missing system calls.
summary:     Syscall Emulation: Add stat64 syscall.

syscall_emul, sysemul or syscemul get my vote