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3619e94ad7
Current document about how to boot VxWorks is limited. Add several chapters in README.vxworks to document this. Signed-off-by: Bin Meng <bmeng.cn@gmail.com> Reviewed-by: Tom Rini <trini@konsulko.com>
86 lines
3.6 KiB
Plaintext
86 lines
3.6 KiB
Plaintext
#
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# Copyright (C) 2013, Miao Yan <miao.yan@windriver.com>
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# Copyright (C) 2015, Bin Meng <bmeng.cn@gmail.com>
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#
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# SPDX-License-Identifier: GPL-2.0+
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#
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VxWorks Support
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===============
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This document describes the information about U-Boot loading VxWorks kernel.
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Status
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------
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U-Boot supports loading VxWorks kernels via 'bootvx' and 'bootm' commands.
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For booting old kernels (6.9.x) on PowerPC and ARM, and all kernel versions
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on other architectures, 'bootvx' shall be used. For booting VxWorks 7 kernels
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on PowerPC and ARM, 'bootm' shall be used.
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64-bit x86 kernel cannot be loaded as of today.
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VxWork 7 on PowerPC and ARM
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---------------------------
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From VxWorks 7, VxWorks starts adopting device tree as its hardware decription
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mechansim (for PowerPC and ARM), thus requiring boot interface changes.
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This section will describe the new interface.
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For PowerPC, the calling convention of the new VxWorks entry point conforms to
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the ePAPR standard, which is shown below (see ePAPR for more details):
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void (*kernel_entry)(fdt_addr, 0, 0, EPAPR_MAGIC, boot_IMA, 0, 0)
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For ARM, the calling convention is show below:
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void (*kernel_entry)(void *fdt_addr)
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When booting new VxWorks kernel (uImage format), the parameters passed to bootm
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is like below:
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bootm <kernel image address> - <device tree address>
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VxWorks bootline
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----------------
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When using 'bootvx', the kernel bootline must be prepared by U-Boot at a
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board-specific address before loading VxWorks. U-Boot supplies its address
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via "bootaddr" environment variable. To check where the bootline should be
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for a specific board, go to the VxWorks BSP for that board, and look for a
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parameter called BOOT_LINE_ADRS. Assign its value to "bootaddr". A typical
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value for "bootaddr" is 0x101200.
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If a "bootargs" variable is defined, its content will be copied to the memory
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location pointed by "bootaddr" as the kernel bootline. If "bootargs" is not
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there, command 'bootvx' can construct a valid bootline using the following
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environments variables: bootdev, bootfile, ipaddr, netmask, serverip,
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gatewayip, hostname, othbootargs.
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When using 'bootm', just define "bootargs" in the environment and U-Boot will
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handle bootline fix up for the kernel dtb automatically.
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Serial console
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--------------
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It's very common that VxWorks BSPs configure a different baud rate for the
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serial console from what is being used by U-Boot. For example, VxWorks tends
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to use 9600 as the default baud rate on all x86 BSPs while U-Boot uses 115200.
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Please configure both U-Boot and VxWorks to use the same baud rate, or it may
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look like VxWorks hangs somewhere as nothing outputs on the serial console.
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x86-specific information
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------------------------
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Before loading an x86 kernel, two additional environment variables need to be
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provided. They are "e820data" and "e820info", which represent the address of
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E820 table and E820 information (defined by VxWorks) in system memory.
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Check VxWorks kernel configuration to look for BIOS_E820_DATA_START and
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BIOS_E820_INFO_START, and assign their values to "e820data" and "e820info"
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accordingly. If neither of these two are supplied, U-Boot assumes a default
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location at 0x4000 for "e820data" and 0x4a00 for "e820info". Typical values
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for "e820data" and "e820info" are 0x104000 and 0x104a00. But there is one
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exception on Intel Galileo, where "e820data" and "e820info" should be left
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unset, which assume the default location for VxWorks.
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Note since currently U-Boot does not support ACPI yet, VxWorks kernel must
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be configured to use MP table and virtual wire interrupt mode. This requires
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INCLUDE_MPTABLE_BOOT_OP and INCLUDE_VIRTUAL_WIRE_MODE to be included in a
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VxWorks kernel configuration.
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