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