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- # SPDX-License-Identifier: GPL-2.0+
- #
- # Copyright (C) 2013, Miao Yan <miao.yan@windriver.com>
- # Copyright (C) 2015-2018, Bin Meng <bmeng.cn@gmail.com>
- # Copyright (C) 2019, Lihua Zhao <lihua.zhao@windriver.com>
- VxWorks Support
- ===============
- This document describes the information about U-Boot loading VxWorks kernel.
- Status
- ------
- U-Boot supports loading VxWorks kernels via 'bootvx' and 'bootm' commands.
- For booting old kernels (6.9.x) on PowerPC and ARM, and all kernel versions
- on other architectures, 'bootvx' shall be used. For booting VxWorks 7 kernels
- on PowerPC and ARM, 'bootm' shall be used.
- With CONFIG_EFI_LOADER option, it's possible to chain load a VxWorks x86 kernel
- via the UEFI boot loader application for VxWorks loaded by 'bootefi' command.
- VxWorks 7 on PowerPC and ARM
- ---------------------------
- From VxWorks 7, VxWorks starts adopting device tree as its hardware description
- mechanism (for PowerPC and ARM), thus requiring boot interface changes.
- This section will describe the new interface.
- Since VxWorks 7 SR0640 release, VxWorks starts using Linux compatible standard
- DTB for some boards. With that, the exact same bootm flow as used by Linux is
- used, which includes board-specific DTB fix up. To keep backward compatibility,
- only when the least significant bit of flags in bootargs is set, the standard
- DTB will be used. Otherwise it falls back to the legacy bootm flow.
- For legacy bootm flow, make sure the least significant bit of flags in bootargs
- is cleared. The calling convention is described below:
- For PowerPC, the calling convention of the new VxWorks entry point conforms to
- the ePAPR standard, which is shown below (see ePAPR for more details):
- void (*kernel_entry)(fdt_addr, 0, 0, EPAPR_MAGIC, boot_IMA, 0, 0)
- For ARM, the calling convention is shown below:
- void (*kernel_entry)(void *fdt_addr)
- When using the Linux compatible standard DTB, the calling convention of VxWorks
- entry point is exactly the same as the Linux kernel.
- When booting a VxWorks 7 kernel (uImage format), the parameters passed to bootm
- is like below:
- bootm <kernel image address> - <device tree address>
- VxWorks bootline
- ----------------
- When using 'bootvx', the kernel bootline must be prepared by U-Boot at a
- board-specific address before loading VxWorks. U-Boot supplies its address
- via "bootaddr" environment variable. To check where the bootline should be
- for a specific board, go to the VxWorks BSP for that board, and look for a
- parameter called BOOT_LINE_ADRS. Assign its value to "bootaddr". A typical
- value for "bootaddr" on an x86 board is 0x101200.
- If a "bootargs" variable is defined, its content will be copied to the memory
- location pointed by "bootaddr" as the kernel bootline. If "bootargs" is not
- there, command 'bootvx' can construct a valid bootline using the following
- environments variables: bootdev, bootfile, ipaddr, netmask, serverip,
- gatewayip, hostname, othbootargs.
- When using 'bootm', just define "bootargs" in the environment and U-Boot will
- handle bootline fix up for the kernel dtb automatically.
- When using 'bootefi' to chain load an x86 kernel, the UEFI boot loader
- application for VxWorks takes care of the kernel bootline preparation.
- Serial console
- --------------
- It's very common that VxWorks BSPs configure a different baud rate for the
- serial console from what is being used by U-Boot. For example, VxWorks tends
- to use 9600 as the default baud rate on all x86 BSPs while U-Boot uses 115200.
- Please configure both U-Boot and VxWorks to use the same baud rate, or it may
- look like VxWorks hangs somewhere as nothing outputs on the serial console.
- x86-specific information
- ------------------------
- Before direct loading an x86 kernel via 'bootvx', one additional environment
- variable need to be provided. This is "vx_phys_mem_base", which represent the
- physical memory base address of VxWorks.
- Check VxWorks kernel configuration to look for LOCAL_MEM_LOCAL_ADRS. For
- VxWorks 7, this is normally a virtual address and you need find out its
- corresponding physical address and assign its value to "vx_phys_mem_base".
- For boards on which ACPI is not supported by U-Boot yet, VxWorks kernel must
- 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
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