7c672abc12
RST conversion is happily mostly behind us.
- A new document on reproducible builds.
- We finally got around to zapping the documentation for hardware support
that was removed in 2004; one doesn't want to rush these things.
- The usual assortment of fixes, typo corrections, etc.
You'll still find a handful of annoying conflicts against other trees,
mostly tied to the last RST conversions; resolutions are straightforward
and the linux-next ones are good.
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Merge tag 'docs-5.4' of git://git.lwn.net/linux
Pull documentation updates from Jonathan Corbet:
"It's a somewhat calmer cycle for docs this time, as the churn of the
mass RST conversion is happily mostly behind us.
- A new document on reproducible builds.
- We finally got around to zapping the documentation for hardware
support that was removed in 2004; one doesn't want to rush these
things.
- The usual assortment of fixes, typo corrections, etc"
* tag 'docs-5.4' of git://git.lwn.net/linux: (67 commits)
Documentation: kbuild: Add document about reproducible builds
docs: printk-formats: Stop encouraging use of unnecessary %h[xudi] and %hh[xudi]
Documentation: Add "earlycon=sbi" to the admin guide
doc🔒 remove reference to clever use of read-write lock
devices.txt: improve entry for comedi (char major 98)
docs: mtd: Update spi nor reference driver
doc: arm64: fix grammar dtb placed in no attributes region
Documentation: sysrq: don't recommend 'S' 'U' before 'B'
mailmap: Update email address for Quentin Perret
docs: ftrace: clarify when tracing is disabled by the trace file
docs: process: fix broken link
Documentation/arm/samsung-s3c24xx: Remove stray U+FEFF character to fix title
Documentation/arm/sa1100/assabet: Fix 'make assabet_defconfig' command
Documentation/arm/sa1100: Remove some obsolete documentation
docs/zh_CN: update Chinese howto.rst for latexdocs making
Documentation: virt: Fix broken reference to virt tree's index
docs: Fix typo on pull requests guide
kernel-doc: Allow anonymous enum
Documentation: sphinx: Don't parse socket() as identifier reference
Documentation: sphinx: Add missing comma to list of strings
...
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2.2 KiB
ReStructuredText
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ReStructuredText
=================================
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Boot image header in RISC-V Linux
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=================================
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:Author: Atish Patra <atish.patra@wdc.com>
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:Date: 20 May 2019
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This document only describes the boot image header details for RISC-V Linux.
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TODO:
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Write a complete booting guide.
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The following 64-byte header is present in decompressed Linux kernel image::
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u32 code0; /* Executable code */
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u32 code1; /* Executable code */
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u64 text_offset; /* Image load offset, little endian */
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u64 image_size; /* Effective Image size, little endian */
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u64 flags; /* kernel flags, little endian */
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u32 version; /* Version of this header */
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u32 res1 = 0; /* Reserved */
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u64 res2 = 0; /* Reserved */
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u64 magic = 0x5643534952; /* Magic number, little endian, "RISCV" */
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u32 magic2 = 0x56534905; /* Magic number 2, little endian, "RSC\x05" */
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u32 res4; /* Reserved for PE COFF offset */
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This header format is compliant with PE/COFF header and largely inspired from
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ARM64 header. Thus, both ARM64 & RISC-V header can be combined into one common
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header in future.
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Notes
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=====
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- This header can also be reused to support EFI stub for RISC-V in future. EFI
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specification needs PE/COFF image header in the beginning of the kernel image
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in order to load it as an EFI application. In order to support EFI stub,
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code0 should be replaced with "MZ" magic string and res5(at offset 0x3c) should
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point to the rest of the PE/COFF header.
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- version field indicate header version number
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========== =============
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Bits 0:15 Minor version
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Bits 16:31 Major version
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========== =============
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This preserves compatibility across newer and older version of the header.
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The current version is defined as 0.2.
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- The "magic" field is deprecated as of version 0.2. In a future
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release, it may be removed. This originally should have matched up
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with the ARM64 header "magic" field, but unfortunately does not.
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The "magic2" field replaces it, matching up with the ARM64 header.
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- In current header, the flags field has only one field.
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===== ====================================
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Bit 0 Kernel endianness. 1 if BE, 0 if LE.
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===== ====================================
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- Image size is mandatory for boot loader to load kernel image. Booting will
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fail otherwise.
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