multiboot: Allow for headless boots

common/protos/multiboot1.c

@@ -317,7 +317,7 @@ noreturn void multiboot1_load(char *config, char *cmdline) {
             struct fb_info fbinfo;
             if (!fb_init(&fbinfo, req_width, req_height, req_bpp)) {
 #if defined (UEFI)
-                panic(true, "multiboot1: Failed to set video mode");
+                goto skip_modeset;
 #elif defined (BIOS)
                 size_t rows, cols;
                 init_vga_textmode(&rows, &cols, false);
@@ -348,7 +348,7 @@ noreturn void multiboot1_load(char *config, char *cmdline) {
             print("multiboot1: Warning: Cannot use text mode with UEFI\n");
             struct fb_info fbinfo;
             if (!fb_init(&fbinfo, 0, 0, 0)) {
-                panic(true, "multiboot1: Failed to set video mode");
+                goto skip_modeset;
             }
             multiboot1_info->fb_addr    = (uint64_t)fbinfo.framebuffer_addr;
             multiboot1_info->fb_width   = fbinfo.framebuffer_width;
@@ -376,6 +376,8 @@ noreturn void multiboot1_load(char *config, char *cmdline) {
         }
 
         multiboot1_info->flags |= (1 << 12);
+
+skip_modeset:;
     } else {
 #if defined (UEFI)
         panic(true, "multiboot1: Cannot use text mode with UEFI.");

common/protos/multiboot2.c

@@ -109,6 +109,8 @@ noreturn void multiboot2_load(char *config, char* cmdline) {
 
     bool is_elf_info_requested = false;
 
+    bool is_framebuffer_required = false;
+
     uint64_t entry_point = 0xffffffff;
 
     // Iterate through the entries...
@@ -143,7 +145,9 @@ noreturn void multiboot2_load(char *config, char* cmdline) {
                                 case MULTIBOOT_TAG_TYPE_EFI64_IH:
                             #endif
                         #endif
+                            break;
                         case MULTIBOOT_TAG_TYPE_FRAMEBUFFER:
+                            is_framebuffer_required = is_required;
                             break;
                         case MULTIBOOT_TAG_TYPE_ACPI_NEW:
                             is_new_acpi_required = is_required;
@@ -521,7 +525,11 @@ noreturn void multiboot2_load(char *config, char* cmdline) {
                 tag->common.framebuffer_bpp = 16;
                 tag->common.framebuffer_type = MULTIBOOT_FRAMEBUFFER_TYPE_EGA_TEXT;
 #elif defined (UEFI)
-                panic(true, "multiboot2: Failed to set video mode");
+                if (is_framebuffer_required) {
+                    panic(true, "multiboot2: Failed to set video mode");
+                } else {
+                    goto skip_modeset;
+                }
 #endif
             } else {
                 tag->common.framebuffer_addr = fbinfo.framebuffer_addr;
@@ -543,8 +551,13 @@ noreturn void multiboot2_load(char *config, char* cmdline) {
             print("multiboot2: Warning: Cannot use text mode with UEFI\n");
             struct fb_info fbinfo;
             if (!fb_init(&fbinfo, 0, 0, 0)) {
-                panic(true, "multiboot2: Failed to set video mode");
+                if (is_framebuffer_required) {
+                    panic(true, "multiboot2: Failed to set video mode");
+                } else {
+                    goto skip_modeset;
+                }
             }
+
             tag->common.framebuffer_addr = fbinfo.framebuffer_addr;
             tag->common.framebuffer_pitch = fbinfo.framebuffer_pitch;
             tag->common.framebuffer_width = fbinfo.framebuffer_width;
@@ -572,6 +585,8 @@ noreturn void multiboot2_load(char *config, char* cmdline) {
         }
 
         append_tag(info_idx, &tag->common);
+
+skip_modeset:;
     }
 
     //////////////////////////////////////////////

test/multiboot.c

@@ -23,7 +23,7 @@ void multiboot_main(uint32_t magic, struct multiboot1_info *info) {
     {
         struct multiboot1_module *start = (struct multiboot1_module *)info->mods_addr;
         struct multiboot1_module *end = (struct multiboot1_module *)(info->mods_addr + info->mods_count);
-    
+
         e9_printf("\t modules:");
         for (struct multiboot1_module* entry = start; entry < end; entry++) {
             e9_printf("\t\t begin=%x", entry->begin);
@@ -32,29 +32,27 @@ void multiboot_main(uint32_t magic, struct multiboot1_info *info) {
         }
     }
 
-    // TODO(Andy-Python-Programmer): ELF sections are unimplemented
-
     {
         struct multiboot1_mmap_entry *start = (struct multiboot1_mmap_entry *)info->mmap_addr;
         struct multiboot1_mmap_entry *end = (struct multiboot1_mmap_entry *)(info->mmap_addr + info->mmap_length);
 
-        e9_printf("\t useable_entries_mmap:");
+        e9_printf("\t usable_entries_mmap:");
 
         size_t total_mem = 0;
 
-        // For now we only print the useable memory map entries since
+        // For now we only print the usable memory map entries since
         // printing the whole memory map blows my terminal up. We also
         // iterate through the avaliable memory map entries and add up
-        // to find the total amount of useable memory.
+        // to find the total amount of usable memory.
         for (struct multiboot1_mmap_entry* entry = start; entry < end; entry++) {
-            // Check if the memory map entry is marked as useable!
+            // Check if the memory map entry is marked as usable!
             if (entry->type != 1) {
                 continue;
             }
 
             e9_printf("\t\t addr=%x", entry->addr);
             e9_printf("\t\t length=%x", entry->len);
-            e9_printf("\t\t type=Useable");
+            e9_printf("\t\t type=Usable");
 
             // Now this might be a bit confusing since but `entry->size` represents the
             // is the size of the associated structure in bytes and `entry->len` represents the
@@ -91,4 +89,4 @@ void multiboot_main(uint32_t magic, struct multiboot1_info *info) {
 
 out:
     for (;;);
-}
+}