doc: vxworks: Update x86 specific instructions
This updates the doc of booting VxWorks, like loading an x64 kernel,
and how to make VxWorks graphics console driver work.
Signed-off-by: Bin Meng <bmeng.cn@gmail.com>
diff --git a/doc/README.vxworks b/doc/README.vxworks
index 3f9b8c1..3239c5b 100644
--- a/doc/README.vxworks
+++ b/doc/README.vxworks
@@ -17,8 +17,6 @@
on other architectures, 'bootvx' shall be used. For booting VxWorks 7 kernels
on PowerPC and ARM, 'bootm' shall be used.
-64-bit x86 kernel cannot be loaded as of today.
-
VxWorks 7 on PowerPC and ARM
---------------------------
From VxWorks 7, VxWorks starts adopting device tree as its hardware decription
@@ -79,3 +77,22 @@
be configured to use MP table and virtual wire interrupt mode. This requires
INCLUDE_MPTABLE_BOOT_OP and INCLUDE_VIRTUAL_WIRE_MODE to be included in a
VxWorks kernel configuration.
+
+Both 32-bit x86 and 64-bit x64 kernels can be loaded.
+
+There are two types of graphics console drivers in VxWorks. One is the 80x25
+VGA text mode driver. The other one is the EFI console bitmapped graphics mode
+driver. To make these drivers function, U-Boot needs to load and run the VGA
+BIOS of the graphics card first.
+
+ - If the kernel is configured with 80x25 VGA text mode driver,
+ CONFIG_FRAMEBUFFER_SET_VESA_MODE must be unset in U-Boot.
+ - If the kernel is configured with bitmapped graphics mode driver,
+ CONFIG_FRAMEBUFFER_SET_VESA_MODE need remain set but care must be taken
+ at which VESA mode is to be set. The supported pixel format is 32-bit
+ RGBA, hence the available VESA mode can only be one of the following:
+ * FRAMEBUFFER_VESA_MODE_10F
+ * FRAMEBUFFER_VESA_MODE_112
+ * FRAMEBUFFER_VESA_MODE_115
+ * FRAMEBUFFER_VESA_MODE_118
+ * FRAMEBUFFER_VESA_MODE_11B