From fa4ff5facf837f280d15400ff44f102dc6d31d3a Mon Sep 17 00:00:00 2001
From: Josh Holtrop <jholtrop@gmail.com>
Date: Thu, 22 Oct 2020 22:03:43 -0400
Subject: [PATCH] load some multiboot2 info after the framebuffer is
 initialized

---
 src/hos_main.c   |  6 +++++-
 src/mbinfo.c     | 51 ++++++++++++++++++++++++++++++++++++++++++++----
 src/mbinfo.h     |  4 +++-
 src/mem.h        |  2 ++
 src/multiboot2.h |  7 ++++++-
 5 files changed, 63 insertions(+), 7 deletions(-)

diff --git a/src/hos_main.c b/src/hos_main.c
index bf1cd0d..d002f47 100644
--- a/src/hos_main.c
+++ b/src/hos_main.c
@@ -5,11 +5,15 @@
 
 void hos_main(uint32_t mbinfo_addr)
 {
-    mbinfo_init(mbinfo_addr);
+    if (!mbinfo_init(mbinfo_addr))
+    {
+        return;
+    }
     if (!fb_ready())
     {
         return;
     }
     klog_init();
     klog_printf("Welcome to HOS!\n");
+    mbinfo_load();
 }
diff --git a/src/mbinfo.c b/src/mbinfo.c
index 8af9d0d..48712f6 100644
--- a/src/mbinfo.c
+++ b/src/mbinfo.c
@@ -1,10 +1,31 @@
 #include "multiboot2.h"
 #include "fb.h"
+#include "mem.h"
+#include <stdint.h>
+#include "klog.h"
 
-static void mbinfo_process_tag(multiboot2_info_tag_t * tag)
+static uint32_t mbinfo[2048];
+
+static void mbinfo_process_tag(const multiboot2_info_tag_t * tag)
 {
     switch (tag->type)
     {
+    case MULTIBOOT2_INFO_BOOT_COMMAND_LINE:
+        {
+            multiboot2_info_boot_command_line_t * cl =
+                (multiboot2_info_boot_command_line_t *)tag;
+            klog_printf("Kernel boot command line: '%s'\n", cl->string);
+        }
+        break;
+
+    case MULTIBOOT2_INFO_BOOT_LOADER_NAME:
+        {
+            multiboot2_info_boot_loader_name_t * bln =
+                (multiboot2_info_boot_loader_name_t *)tag;
+            klog_printf("Boot loader: '%s'\n", bln->string);
+        }
+        break;
+
     case MULTIBOOT2_INFO_FRAMEBUFFER_INFO:
         {
             multiboot2_info_framebuffer_info_t * fbinfo =
@@ -18,12 +39,34 @@ static void mbinfo_process_tag(multiboot2_info_tag_t * tag)
     }
 }
 
-void mbinfo_init(uint32_t mbinfo_addr)
+static void process_tags(const multiboot2_info_tag_t * tag, bool init)
 {
-    multiboot2_info_tag_t * tag = (multiboot2_info_tag_t *)(mbinfo_addr + sizeof(multiboot2_info_header_t));
     while (tag->type != 0u)
     {
-        mbinfo_process_tag(tag);
+        if ((init && (tag->type == MULTIBOOT2_INFO_FRAMEBUFFER_INFO)) ||
+                (!init && (tag->type != MULTIBOOT2_INFO_FRAMEBUFFER_INFO)))
+        {
+            mbinfo_process_tag(tag);
+        }
         tag = multiboot2_info_next_tag(tag);
     }
 }
+
+bool mbinfo_init(uint32_t mbinfo_addr)
+{
+    multiboot2_info_header_t * mbinfo_header = (multiboot2_info_header_t *)mbinfo_addr;
+    if (mbinfo_header->total_size <= sizeof(mbinfo))
+    {
+        memcpy32(mbinfo, mbinfo_header, mbinfo_header->total_size / 4u);
+        multiboot2_info_tag_t * tag = (multiboot2_info_tag_t *)(mbinfo + sizeof(multiboot2_info_header_t) / 4u);
+        process_tags(tag, true);
+        return true;
+    }
+    return false;
+}
+
+void mbinfo_load(void)
+{
+    multiboot2_info_tag_t * tag = (multiboot2_info_tag_t *)(mbinfo + sizeof(multiboot2_info_header_t) / 4u);
+    process_tags(tag, false);
+}
diff --git a/src/mbinfo.h b/src/mbinfo.h
index 314f675..bd95bdf 100644
--- a/src/mbinfo.h
+++ b/src/mbinfo.h
@@ -2,7 +2,9 @@
 #define MBINFO_H
 
 #include <stdint.h>
+#include <stdbool.h>
 
-void mbinfo_init(uint32_t mbinfo_addr);
+bool mbinfo_init(uint32_t mbinfo_addr);
+void mbinfo_load(void);
 
 #endif
diff --git a/src/mem.h b/src/mem.h
index e5ead99..fd843a2 100644
--- a/src/mem.h
+++ b/src/mem.h
@@ -1,6 +1,8 @@
 #ifndef MEM_H
 #define MEM_H
 
+#include <stddef.h>
+
 static inline void memcpy(void * dest, const void * src, size_t n)
 {
     uint32_t r0, r1, r2;
diff --git a/src/multiboot2.h b/src/multiboot2.h
index f5603a5..3881bb9 100644
--- a/src/multiboot2.h
+++ b/src/multiboot2.h
@@ -70,7 +70,12 @@ typedef struct {
 
 typedef struct {
     multiboot2_info_tag_t header;
-    uint8_t string[];
+    char string[];
+} multiboot2_info_boot_command_line_t;
+
+typedef struct {
+    multiboot2_info_tag_t header;
+    char string[];
 } multiboot2_info_boot_loader_name_t;
 
 typedef struct {