os-workshop

commit dc3894952fe274f58ddb0751d171a5dc234104d2
parent 130e7ea6690bcc7fa837bda1adc8ab7385304925
Author: Brian Swetland <swetland@frotz.net>
Date:   Mon,  9 May 2022 11:10:38 -0700

build: improve linker scripts

- more complete coverage of common sections
- __bss_start, __bss_end, etc needed by init code

Diffstat:
M
Makefile
 | 
2
+-
A
hw/app.ram.ld
 | 
6
++++++
D
hw/boot.ld
 | 
14
--------------
A
hw/boot.ram.ld
 | 
6
++++++
A
hw/common.ram.ld
 | 
42
++++++++++++++++++++++++++++++++++++++++++
D
hw/simple.ld
 | 
14
--------------
M
project/boot.app.mk
 | 
2
+-

7 files changed, 56 insertions(+), 30 deletions(-)
diff --git a/Makefile b/Makefile
@@ -37,7 +37,7 @@ ARCHFLAGS += -static -nostdlib -nostartfiles -ffreestanding
 ARCHFLAGS += -ffunction-sections -fdata-sections
 ARCHFLAGS += -fno-builtin -fno-strict-aliasing
 
-LDSCRIPT := hw/simple.ld
+LDSCRIPT := hw/app.ram.ld
 
 BUILD := out
 
diff --git a/hw/app.ram.ld b/hw/app.ram.ld
@@ -0,0 +1,6 @@
+
+MEMORY {
+	RAM (rwx) : ORIGIN = 0x40008000, LENGTH = 0x7F8000
+}
+
+INCLUDE "hw/common.ram.ld"
diff --git a/hw/boot.ld b/hw/boot.ld
@@ -1,14 +0,0 @@
-OUTPUT_ARCH( "riscv" )
-ENTRY(_start)
-
-SECTIONS
-{
-  . = 0x40000000;
-  .start  : { *(.start) }
-  .text   : { *(.text*) }
-  .rodata : { *(.rodata*) }
-  .data   : { *(.data*) }
-  .bss    : { *(.bss*) }
-  _end = .;
-}
-
diff --git a/hw/boot.ram.ld b/hw/boot.ram.ld
@@ -0,0 +1,6 @@
+
+MEMORY {
+	RAM (rwx) : ORIGIN = 0x40000000, LENGTH = 0x8000
+}
+
+INCLUDE "hw/common.ram.ld"
diff --git a/hw/common.ram.ld b/hw/common.ram.ld
@@ -0,0 +1,42 @@
+
+ENTRY(_start)
+
+SECTIONS {
+	/* RX code */
+	.text : {
+		KEEP(*(.start))
+		*(.text .text*)
+		*(.gnu.linkonce.t.*)
+	} > RAM
+
+	/* RO data */
+	.rodata : {
+		. = ALIGN(4096);
+		__rodata_start = .;
+		*(.rodata .rodata.* .gnu.linkonce.r.*)
+		. = ALIGN(4);
+		__rodata_end = .;
+	} > RAM
+
+	/* collect any extra sections here */
+	. = .;
+
+	/* RW data */
+	.data : {
+		. = ALIGN(4096);
+		__data_start = .;
+		*(.data .data.* .gnu.linkonce.d.*)
+		*(.got*)
+		*(.dynamic)
+		. = ALIGN(4);
+		__data_end = .;
+	} > RAM
+
+	.bss : {
+		__bss_start = .;
+		*(.bss .bss.*)
+		*(.gnu.linkonce.b.*)
+		. = ALIGN(4);
+		__bss_end = .;
+	} > RAM
+}
diff --git a/hw/simple.ld b/hw/simple.ld
@@ -1,14 +0,0 @@
-OUTPUT_ARCH( "riscv" )
-ENTRY(_start)
-
-SECTIONS
-{
-  . = 0x40008000;
-  .start  : { *(.start) }
-  .text   : { *(.text*) }
-  .rodata : { *(.rodata*) }
-  .data   : { *(.data*) }
-  .bss    : { *(.bss*) }
-  _end = .;
-}
-
diff --git a/project/boot.app.mk b/project/boot.app.mk
@@ -3,5 +3,5 @@ MOD_NAME := boot
 MOD_SRC := hw/src/start.S boot/entry.S boot/boot.c
 MOD_SRC += hw/src/debug.c
 MOD_LIB := c
-MOD_LDSCRIPT := hw/boot.ld
+MOD_LDSCRIPT := hw/boot.ram.ld
 include make/app.mk