From eb0c943a71930ff28271a7a22dfb29bc4a3ff8ef Mon Sep 17 00:00:00 2001
From: Stephen Marz <stephen.marz@utk.edu>
Date: Sat, 7 Dec 2019 22:04:13 -0500
Subject: [PATCH] Updates to process.

---
 risc_v/ch6/src/lib.rs     |  3 ++-
 risc_v/ch6/src/process.rs | 18 +++++++++++-------
 2 files changed, 13 insertions(+), 8 deletions(-)

diff --git a/risc_v/ch6/src/lib.rs b/risc_v/ch6/src/lib.rs
index 312d80c..b2add65 100755
--- a/risc_v/ch6/src/lib.rs
+++ b/risc_v/ch6/src/lib.rs
@@ -125,6 +125,7 @@ extern "C" fn kinit() -> usize {
 	page::init();
 	kmem::init();
 	let ret = process::init();
+	println!("Init process created at address 0x{:08x}", ret);
 	// We lower the threshold wall so our interrupts can jump over it.
 	plic::set_threshold(0);
 	// VIRTIO = [1..8]
@@ -133,7 +134,7 @@ extern "C" fn kinit() -> usize {
 	// Enable the UART interrupt.
 	plic::enable(10);
 	plic::set_priority(10, 1);
-	println!("UART interrupts have been enabled and are awaiting your command");
+	println!("UART interrupts have been enabled and are awaiting your command.");
 	println!("Getting ready for first process.");
 	println!("Issuing the first context-switch timer.");
 	unsafe {
diff --git a/risc_v/ch6/src/process.rs b/risc_v/ch6/src/process.rs
index b4c6724..d81d548 100644
--- a/risc_v/ch6/src/process.rs
+++ b/risc_v/ch6/src/process.rs
@@ -24,7 +24,7 @@ use alloc::collections::vec_deque::VecDeque;
 const STACK_PAGES: usize = 2;
 // We want to adjust the stack to be at the bottom of the memory allocation
 // regardless of where it is on the kernel heap.
-const STACK_ADDR_ADJ: usize = 0x3f_0000_0000;
+const STACK_ADDR: usize = 0xf_0000_0000;
 // const STACK_ADDR_ADJ: usize = 0;
 // All processes will have a defined starting point in virtual memory.
 const PROCESS_STARTING_ADDR: usize = 0x2000_0000;
@@ -34,6 +34,11 @@ const PROCESS_STARTING_ADDR: usize = 0x2000_0000;
 // that we made before and its job is to store all processes.
 // We will have this list OWN the process. So, anytime we want
 // the process, we will consult the process list.
+// Using an Option here is one method of creating a "lazy static".
+// Rust requires that all statics be initialized, but all
+// initializations must be at compile-time. We cannot allocate
+// a VecDeque at compile time, so we are somewhat forced to
+// do this.
 static mut PROCESS_LIST: Option<VecDeque<Process>> = None;
 // We can search through the process list to get a new PID, but
 // it's probably easier and faster just to increase the pid:
@@ -167,9 +172,8 @@ impl Process {
 		// to usize first and then add PAGE_SIZE is better.
 		// We also need to set the stack adjustment so that it is at the
 		// bottom of the memory and far away from heap allocations.
-		ret_proc.frame.regs[2] = ret_proc.stack as usize
-		                         + STACK_ADDR_ADJ + PAGE_SIZE
-		                                            * STACK_PAGES;
+		ret_proc.frame.regs[2] = STACK_ADDR + PAGE_SIZE
+		                                           * STACK_PAGES;
 		// Map the stack on the MMU
 		let pt;
 		unsafe {
@@ -180,11 +184,11 @@ impl Process {
 		// memory This gets a little hairy because we need to also map
 		// the function code too.
 		for i in 0..STACK_PAGES {
-			let addr = saddr + i * PAGE_SIZE;
+			let addr = i * PAGE_SIZE;
 			map(
 			    pt,
-			    addr + STACK_ADDR_ADJ,
-			    addr,
+			    STACK_ADDR + addr,
+			    saddr + addr,
 			    EntryBits::UserReadWrite.val(),
 			    0,
 			);