5 files changed, 159 insertions, 0 deletions
diff --git a/sys/kern/entry.S b/sys/kern/entry.S
new file mode 100644
index 0000000..5ad0490
--- /dev/null
+++ b/sys/kern/entry.S
@@ -0,0 +1,39 @@
+.section ".text.init"
+
+.globl _start
+_start:
+        csrw       satp, zero
+        csrw       sie, zero
+        csrw       sip, zero
+
+        .option push
+        .option norelax
+        la         gp, __global_pointer$
+        .option pop
+
+        la         sp, __stack_start
+        li         t1, PAGE_SIZE 
+        mul        t1, t1, a0
+        add        sp, sp, t1
+
+        li         a2, 1
+        lla        a3, _boot_hart
+        amoswap.w  a3, a2, (a3)
+        bnez a3,   _spin
+
+        la         a2, __bss_start
+        la         a3, __bss_end
+1:
+        sd	   zero, (a2)
+        addi       a2, a2, __SIZEOF_POINTER__
+        blt        a2, a3, 1b 
+        
+        call       init
+
+
+_spin:
+	wfi
+	j _spin
+
+.section ".data"
+_boot_hart: .word 0
diff --git a/sys/kern/init.c b/sys/kern/init.c
new file mode 100644
index 0000000..a49c304
--- /dev/null
+++ b/sys/kern/init.c
@@ -0,0 +1,11 @@
+#include <fdt.h>
+#include <kernel_earlyprintf.h>
+
+void 
+init(unsigned long hartid, struct fdt_header *fdt)
+{
+	kernel_earlyputs("booting...\n");
+	if (fdt_uint32(fdt->magic) == FDT_HEADER_MAGIC) 
+		kernel_earlyputs("found flattened device tree!\n");
+
+}
diff --git a/sys/kern/kernel.lds b/sys/kern/kernel.lds
new file mode 100644
index 0000000..2e2fe29
--- /dev/null
+++ b/sys/kern/kernel.lds
@@ -0,0 +1,58 @@
+OUTPUT_ARCH(riscv)
+ENTRY(_start)
+
+SECTIONS
+{
+        . = LOAD_ADDR;
+        . = ALIGN(PAGE_SIZE);
+
+        .text :
+        {
+                PROVIDE(__text_start = .);
+                *(.text.init)
+                *(.text .text.*)
+                . = ALIGN(8);
+                PROVIDE(__text_end = .);
+        }
+        . = ALIGN(PAGE_SIZE);
+
+        PROVIDE(__global_pointer$ = .);
+
+        .rodata :
+        {
+                PROVIDE(__rodata_start = .);
+                *(.rodata .rodata.*)
+                . = ALIGN(8);
+                PROVIDE(__rodata_end = .); 
+        }
+
+        . = ALIGN(PAGE_SIZE);
+
+        .data : 
+        {
+                PROVIDE(__data_start = .);
+                *(.sdata .sdata.*) 
+                *(.data .data.*)
+                *(.readmostly.data)
+                *(*.data)
+                . = ALIGN(8);
+                PROVIDE(__data_end = .);
+        }
+
+        . = ALIGN(PAGE_SIZE); 
+
+	.bss :
+	{
+		PROVIDE(__bss_start = .);
+		*(.sbss .sbss.*)
+		*(.bss .bss.*)
+		. = ALIGN(8);
+		PROVIDE(__bss_end = .);
+	}
+
+	. = ALIGN(PAGE_SIZE);
+
+        PROVIDE(__stack_start = .);
+        PROVIDE(__stack_end = __stack_start + (PAGE_SIZE * NPROC));
+        PROVIDE(__heap_start = __stack_end);
+}
diff --git a/sys/kern/kernel_earlyprintf.c b/sys/kern/kernel_earlyprintf.c
new file mode 100644
index 0000000..e6c85c4
--- /dev/null
+++ b/sys/kern/kernel_earlyprintf.c
@@ -0,0 +1,11 @@
+#include <kernel_earlyprintf.h>
+#include <sbi.h>
+
+int
+kernel_earlyputs(const char *str)
+{
+	do {
+		sbi_console_putchar(*str);
+	} while (*(str++) != '\0');
+}
+
diff --git a/sys/kern/mm/kalloc.c b/sys/kern/mm/kalloc.c
new file mode 100644
index 0000000..b17d432
--- /dev/null
+++ b/sys/kern/mm/kalloc.c
@@ -0,0 +1,40 @@
+#include <stddef.h>
+#include <string.h>
+#include <mm/kalloc.h>
+
+typedef struct freenode {
+	struct freenode *next;
+} freenode_t;
+
+freenode_t *head = NULL;
+
+void *
+kalloc(void) 
+{
+	freenode_t *p = head;
+
+	if (p == NULL)
+		return NULL;
+
+	head = p->next;
+	return p;
+}
+
+void *
+kzalloc(void)
+{
+	freenode_t *p = kalloc();
+	memset(p, 0, PAGE_SIZE);
+	return p;
+}
+
+void
+kfree(void *p)
+{
+	if (p == NULL || (unsigned long)p % PAGE_SIZE)
+		return;
+
+	freenode_t *tmp = head;
+	head = p;
+	head->next = tmp;
+}