Stub out madvise syscall (#145)

Implement clock_gettime syscall (#139)

Bump the Linux version PK claims to support

This makes it more compatible with recent glibc.

Stub out sys_prlimit64

avoid non-standard predefined macros

For RV32, mmap offset is in 4 KiB increments

Add syscall stubs to get through libpthread initializers

when -s is passed, print time, instret, cycle, and CPI

Remove uarch counters

We'll re-add support for the generic performance counter facility once
it exists.

Move DRAM to high addresses

pk: proxy chdir syscall to fesvr

Don't assume existence of uarch counters

Refactor pk, bbl, machine into separate libraries

Yuck.

Disentangle PK and BBL a bit

Fix struct stat size mismatch for RV32

Remove incorrect code supporting ELF32 on RV64 and vice-versa

This is technically possible by running an RV32 supervisor on an
RV64 machine, but the M-mode and S-mode code would need to be
compiled and linked separately.

add renameat syscall

Add ftruncate syscall

Stub out a few system calls

Split pk functionality into pk and bbl

pk is now an AEE only (i.e. it can only execute user programs).
bbl is now an SEE only (i.e. it can only host kernels).

Update to new privileged spec

work in progress on new supervisor spec

return -ENOSYS for ioctl, rather than aborting

Support linkat, unlinkat, mkdirat syscalls

Also, old-style syscalls e.g. open are now implemented with e.g. openat.

Don't rely on the C library

Support glibc 2.20 programs

Fix uarch counter printout type.

Added "-c" option to track uarch counter info.

Changes to allow spike & RTL behavior to better match each other.

- EI turned off on sys_exit.
- IM/IP cleared on start.
- badvaddr only saved to tf on page faults.

Allow mmap to map new segments larger than 1 page on top of existing mappings and add mprotect syscall

Add several syscalls, and move syscall header file from newlib
syscalls added (openat, access, accessat, faccessat, etc.)

Abandon MIPS convention for indicating syscall errors in register a3

Add times syscall

Update to new privileged ISA

Add gettimeofday syscall

Add some syscalls

Remove extraneous printk

Support Linux ABI and (optionally) virtual memory

add BSD license

Synced up PK with supervisor changes/asm syntax

You must upgrade to the latest compiler and ISA
simulator to build and run this version of the PK.

temporary undoing of renaming

Renamed packages

[pk] made PK smaller

[pk] fixed timer interrupt bug, etc.

[pk,sim,xcc] get rid of at register, introduce tp register

[pk, sim] added FPU emulation support to proxy kernel

[pk] new register mappings

[pk,fesvr] improved proxykernel build system

Now uses a modified MCPPBS. Add --host=riscv to configure path.

Front-end server now just searches PATH for riscv-pk, so just install the pk
to somewhere in your path.