From 32075c0a70c262faef86220b9f42db4836962f9e Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Thu, 16 Sep 2021 06:50:15 +0000
Subject: scaffolding for the initrd: init can read files appended to it

currently this is just a text file, but it will be a tar archive later
on
---
 Makefile           | 6 +++++-
 fake_initrd.txt    | 1 +
 src/init/linker.ld | 4 ++++
 src/init/main.c    | 3 +++
 4 files changed, 13 insertions(+), 1 deletion(-)
 create mode 100644 fake_initrd.txt

diff --git a/Makefile b/Makefile
index 9a758cf..def6452 100644
--- a/Makefile
+++ b/Makefile
@@ -44,10 +44,14 @@ out/fs/boot/kernel.bin: src/kernel/linker.ld $(call from_sources, src/kernel/)
 	@$(CC) $(LFLAGS) -T $^ -o $@
 	grub-file --is-x86-multiboot $@
 
-out/fs/boot/init: src/init/linker.ld $(call from_sources, src/init/)
+out/raw_init: src/init/linker.ld $(call from_sources, src/init/)
 	@mkdir -p $(@D)
 	@$(CC) $(LFLAGS) -T $^ -o $@
 
+out/fs/boot/init: out/raw_init fake_initrd.txt
+	@mkdir -p $(@D)
+	@cat $^ > $@
+
 out/fs/boot/grub/grub.cfg: grub.cfg
 	@mkdir -p $(@D)
 	@cp $< $@
diff --git a/fake_initrd.txt b/fake_initrd.txt
new file mode 100644
index 0000000..77a9fda
--- /dev/null
+++ b/fake_initrd.txt
@@ -0,0 +1 @@
+i am NOT a real initrd.
diff --git a/src/init/linker.ld b/src/init/linker.ld
index efb44fd..f2c9d24 100644
--- a/src/init/linker.ld
+++ b/src/init/linker.ld
@@ -17,6 +17,10 @@ SECTIONS
 	{
 		*(.data)
 	}
+
+	_initrd = .; /* is just appended onto the end of the binary */
+	. += 2M;
+
 	_bss_start = .;
 	.bss BLOCK(4K) : ALIGN(4K)
 	{
diff --git a/src/init/main.c b/src/init/main.c
index 265379d..db94d4a 100644
--- a/src/init/main.c
+++ b/src/init/main.c
@@ -8,6 +8,7 @@
 
 extern char _bss_start; // provided by the linker
 extern char _bss_end;
+extern char _initrd;
 
 int tty_fd;
 
@@ -24,6 +25,8 @@ int main(void) {
 		_syscall_exit(argify("couldn't open tty"));
 
 	fs_test();
+
+	_syscall_write(tty_fd, &_initrd, 23);
 	_syscall_exit(argify("my job here is done."));
 }
 
-- 
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