1# SPDX-License-Identifier: GPL-2.0+ 2# 3# Copyright (C) 2013, Miao Yan <miao.yan@windriver.com> 4# Copyright (C) 2015-2018, Bin Meng <bmeng.cn@gmail.com> 5 6VxWorks Support 7=============== 8 9This document describes the information about U-Boot loading VxWorks kernel. 10 11Status 12------ 13U-Boot supports loading VxWorks kernels via 'bootvx' and 'bootm' commands. 14For booting old kernels (6.9.x) on PowerPC and ARM, and all kernel versions 15on other architectures, 'bootvx' shall be used. For booting VxWorks 7 kernels 16on PowerPC and ARM, 'bootm' shall be used. 17 18With CONFIG_EFI_LOADER option, it's possible to chain load a VxWorks x86 kernel 19via the UEFI boot loader application for VxWorks loaded by 'bootefi' command. 20 21VxWorks 7 on PowerPC and ARM 22--------------------------- 23From VxWorks 7, VxWorks starts adopting device tree as its hardware description 24mechanism (for PowerPC and ARM), thus requiring boot interface changes. 25This section will describe the new interface. 26 27For PowerPC, the calling convention of the new VxWorks entry point conforms to 28the ePAPR standard, which is shown below (see ePAPR for more details): 29 30 void (*kernel_entry)(fdt_addr, 0, 0, EPAPR_MAGIC, boot_IMA, 0, 0) 31 32For ARM, the calling convention is shown below: 33 34 void (*kernel_entry)(void *fdt_addr) 35 36When booting a VxWorks 7 kernel (uImage format), the parameters passed to bootm 37is like below: 38 39 bootm <kernel image address> - <device tree address> 40 41VxWorks bootline 42---------------- 43When using 'bootvx', the kernel bootline must be prepared by U-Boot at a 44board-specific address before loading VxWorks. U-Boot supplies its address 45via "bootaddr" environment variable. To check where the bootline should be 46for a specific board, go to the VxWorks BSP for that board, and look for a 47parameter called BOOT_LINE_ADRS. Assign its value to "bootaddr". A typical 48value for "bootaddr" on an x86 board is 0x101200. 49 50If a "bootargs" variable is defined, its content will be copied to the memory 51location pointed by "bootaddr" as the kernel bootline. If "bootargs" is not 52there, command 'bootvx' can construct a valid bootline using the following 53environments variables: bootdev, bootfile, ipaddr, netmask, serverip, 54gatewayip, hostname, othbootargs. 55 56When using 'bootm', just define "bootargs" in the environment and U-Boot will 57handle bootline fix up for the kernel dtb automatically. 58 59When using 'bootefi' to chain load an x86 kernel, the UEFI boot loader 60application for VxWorks takes care of the kernel bootline preparation. 61 62Serial console 63-------------- 64It's very common that VxWorks BSPs configure a different baud rate for the 65serial console from what is being used by U-Boot. For example, VxWorks tends 66to use 9600 as the default baud rate on all x86 BSPs while U-Boot uses 115200. 67Please configure both U-Boot and VxWorks to use the same baud rate, or it may 68look like VxWorks hangs somewhere as nothing outputs on the serial console. 69 70x86-specific information 71------------------------ 72Before direct loading an x86 kernel via 'bootvx', one additional environment 73variable need to be provided. This is "vx_phys_mem_base", which represent the 74physical memory base address of VxWorks. 75 76Check VxWorks kernel configuration to look for LOCAL_MEM_LOCAL_ADRS. For 77VxWorks 7, this is normally a virtual address and you need find out its 78corresponding physical address and assign its value to "vx_phys_mem_base". 79 80For boards on which ACPI is not supported by U-Boot yet, VxWorks kernel must 81be configured to use MP table and virtual wire interrupt mode. This requires 82INCLUDE_MPTABLE_BOOT_OP and INCLUDE_VIRTUAL_WIRE_MODE to be included in a 83VxWorks kernel configuration. 84 85Both 32-bit x86 and 64-bit x64 kernels can be loaded. 86 87There are two types of graphics console drivers in VxWorks. One is the 80x25 88VGA text mode driver. The other one is the EFI console bitmapped graphics mode 89driver. To make these drivers function, U-Boot needs to load and run the VGA 90BIOS of the graphics card first. 91 92 - If the kernel is configured with 80x25 VGA text mode driver, 93 CONFIG_FRAMEBUFFER_SET_VESA_MODE must be unset in U-Boot. 94 - If the kernel is configured with bitmapped graphics mode driver, 95 CONFIG_FRAMEBUFFER_SET_VESA_MODE need remain set but care must be taken 96 at which VESA mode is to be set. The supported pixel format is 32-bit 97 RGBA, hence the available VESA mode can only be one of the following: 98 * FRAMEBUFFER_VESA_MODE_10F 99 * FRAMEBUFFER_VESA_MODE_112 100 * FRAMEBUFFER_VESA_MODE_115 101 * FRAMEBUFFER_VESA_MODE_118 102 * FRAMEBUFFER_VESA_MODE_11B 103