stivale: Add support for extended colour information

STIVALE.md

@@ -179,7 +179,16 @@ struct stivale_struct {
     uint64_t epoch;                 // UNIX epoch at boot, read from system RTC
     uint64_t flags;                 // Flags
                                     // bit 0: 1 if booted with BIOS, 0 if booted with UEFI
+                                    // bit 1: 1 if extended colour information passed, 0 if not
                                     // All other bits undefined.
+    // Extended colour information follows, only access if bit 1 of flags is set.
+    uint8_t  fb_memory_model;       // Memory model: 1=RGB, all other values undefined
+    uint8_t  fb_red_mask_size;      // RGB mask sizes and left shifts
+    uint8_t  fb_red_mask_shift;
+    uint8_t  fb_green_mask_size;
+    uint8_t  fb_green_mask_shift;
+    uint8_t  fb_blue_mask_size;
+    uint8_t  fb_blue_mask_shift;
 } __attribute__((packed));
 ```
 

stage2/protos/stivale.c

@@ -28,6 +28,7 @@ struct stivale_struct stivale_struct = {0};
 
 void stivale_load(char *config, char *cmdline) {
     stivale_struct.flags |= (1 << 0);  // set bit 0 since we are BIOS and not UEFI
+    stivale_struct.flags |= (1 << 1);  // we give colour information
 
     struct file_handle *kernel = conv_mem_alloc(sizeof(struct file_handle));
 
@@ -183,13 +184,21 @@ void stivale_load(char *config, char *cmdline) {
             parse_resolution(&req_width, &req_height, &req_bpp, resolution);
 
         struct vbe_framebuffer_info fbinfo;
-        init_vbe(&fbinfo, req_width, req_height, req_bpp);
+        if (!init_vbe(&fbinfo, req_width, req_height, req_bpp))
+            panic("stivale: Unable to set video mode");
 
-        stivale_struct.framebuffer_addr   = (uint64_t)fbinfo.framebuffer_addr;
-        stivale_struct.framebuffer_width  = fbinfo.framebuffer_width;
-        stivale_struct.framebuffer_height = fbinfo.framebuffer_height;
-        stivale_struct.framebuffer_bpp    = fbinfo.framebuffer_bpp;
-        stivale_struct.framebuffer_pitch  = fbinfo.framebuffer_pitch;
+        stivale_struct.framebuffer_addr    = (uint64_t)fbinfo.framebuffer_addr;
+        stivale_struct.framebuffer_width   = fbinfo.framebuffer_width;
+        stivale_struct.framebuffer_height  = fbinfo.framebuffer_height;
+        stivale_struct.framebuffer_bpp     = fbinfo.framebuffer_bpp;
+        stivale_struct.framebuffer_pitch   = fbinfo.framebuffer_pitch;
+        stivale_struct.fb_memory_model     = STIVALE_FBUF_MMODEL_RGB;
+        stivale_struct.fb_red_mask_size    = fbinfo.red_mask_size;
+        stivale_struct.fb_red_mask_shift   = fbinfo.red_mask_shift;
+        stivale_struct.fb_green_mask_size  = fbinfo.green_mask_size;
+        stivale_struct.fb_green_mask_shift = fbinfo.green_mask_shift;
+        stivale_struct.fb_blue_mask_size   = fbinfo.blue_mask_size;
+        stivale_struct.fb_blue_mask_shift  = fbinfo.blue_mask_shift;
     }
 
     bool want_5lv = level5pg && (stivale_hdr.flags & (1 << 1));

stivale/stivale.h

@@ -41,6 +41,10 @@ struct stivale_mmap_entry {
     uint32_t unused;
 } __attribute__((packed));
 
+enum {
+    STIVALE_FBUF_MMODEL_RGB = 1
+};
+
 struct stivale_struct {
     uint64_t cmdline;
     uint64_t memory_map_addr;
@@ -55,6 +59,14 @@ struct stivale_struct {
     uint64_t modules;
     uint64_t epoch;
     uint64_t flags; // bit 0: 1 if booted with BIOS, 0 if booted with UEFI
+                    // bit 1: 1 if extended colour information passed, 0 if not
+    uint8_t  fb_memory_model;
+    uint8_t  fb_red_mask_size;
+    uint8_t  fb_red_mask_shift;
+    uint8_t  fb_green_mask_size;
+    uint8_t  fb_green_mask_shift;
+    uint8_t  fb_blue_mask_size;
+    uint8_t  fb_blue_mask_shift;
 } __attribute__((packed));
 
 #endif

test/stivale.c

@@ -33,6 +33,17 @@ void stivale_main(struct stivale_struct *info) {
     e9_printf("\tWidth:  %d", info->framebuffer_width);
     e9_printf("\tHeight: %d", info->framebuffer_height);
     e9_printf("\tBPP:    %d", info->framebuffer_bpp);
+    if (info->flags & (1 << 1)) {
+        e9_printf("\tExtended colour information passed:");
+        e9_printf("\t\tMemory model:     %d", info->fb_memory_model);
+        e9_printf("\t\tRed mask size:    %d", info->fb_red_mask_size);
+        e9_printf("\t\tRed mask shift:   %d", info->fb_red_mask_shift);
+        e9_printf("\t\tGreen mask size:  %d", info->fb_green_mask_size);
+        e9_printf("\t\tGreen mask shift: %d", info->fb_green_mask_shift);
+        e9_printf("\t\tBlue mask size:   %d", info->fb_blue_mask_size);
+        e9_printf("\t\tBlue mask shift:  %d", info->fb_blue_mask_shift);
+    }
+
     e9_printf("RSDP at %x", info->rsdp);
 
     e9_printf("Module map at %x with modules:", info->modules);