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| author | Atish Patra <atish.patra@wdc.com> | 2019-06-06 16:08:00 -0700 |
|---|---|---|
| committer | Paul Walmsley <paul.walmsley@sifive.com> | 2019-07-11 11:58:20 -0700 |
| commit | 0f327f2aaad6a87356cbccfa390d4d3b64d0d3b6 (patch) | |
| tree | 5c7b353f5d10434675cbb37a87cb4b21e6af9eb6 /arch/riscv/kernel/head.S | |
| parent | 671f9a3e2e24cdeb2d2856abee7422f093e23e29 (diff) | |
| download | linux-0f327f2aaad6a87356cbccfa390d4d3b64d0d3b6.tar.bz2 | |
RISC-V: Add an Image header that boot loader can parse.
Currently, the last stage boot loaders such as U-Boot can accept only
uImage which is an unnecessary additional step in automating boot
process.
Add an image header that boot loader understands and boot Linux from
flat Image directly.
This header is based on ARM64 boot image header and provides an
opportunity to combine both ARM64 & RISC-V image headers in future.
Also make sure that PE/COFF header can co-exist in the same image so
that EFI stub can be supported for RISC-V in future. EFI specification
needs PE/COFF image header in the beginning of the kernel image in order
to load it as an EFI application. In order to support EFI stub, code0
should be replaced with "MZ" magic string and res4(at offset 0x3c)
should point to the rest of the PE/COFF header (which will be added
during EFI support).
Tested on both QEMU and HiFive Unleashed using OpenSBI + U-Boot + Linux.
Signed-off-by: Atish Patra <atish.patra@wdc.com>
Reviewed-by: Karsten Merker <merker@debian.org>
Tested-by: Karsten Merker <merker@debian.org> (QEMU+OpenSBI+U-Boot)
Tested-by: Kevin Hilman <khilman@baylibre.com> (OpenSBI + U-Boot + Linux)
[paul.walmsley@sifive.com: fixed whitespace in boot-image-header.txt;
converted structure comment to kernel-doc format and added some detail]
Signed-off-by: Paul Walmsley <paul.walmsley@sifive.com>
Diffstat (limited to 'arch/riscv/kernel/head.S')
| -rw-r--r-- | arch/riscv/kernel/head.S | 32 |
1 files changed, 32 insertions, 0 deletions
diff --git a/arch/riscv/kernel/head.S b/arch/riscv/kernel/head.S index e368106f2228..0f1ba17e476f 100644 --- a/arch/riscv/kernel/head.S +++ b/arch/riscv/kernel/head.S @@ -11,9 +11,41 @@ #include <asm/thread_info.h> #include <asm/page.h> #include <asm/csr.h> +#include <asm/image.h> __INIT ENTRY(_start) + /* + * Image header expected by Linux boot-loaders. The image header data + * structure is described in asm/image.h. + * Do not modify it without modifying the structure and all bootloaders + * that expects this header format!! + */ + /* jump to start kernel */ + j _start_kernel + /* reserved */ + .word 0 + .balign 8 +#if __riscv_xlen == 64 + /* Image load offset(2MB) from start of RAM */ + .dword 0x200000 +#else + /* Image load offset(4MB) from start of RAM */ + .dword 0x400000 +#endif + /* Effective size of kernel image */ + .dword _end - _start + .dword __HEAD_FLAGS + .word RISCV_HEADER_VERSION + .word 0 + .dword 0 + .asciz RISCV_IMAGE_MAGIC + .word 0 + .balign 4 + .word 0 + +.global _start_kernel +_start_kernel: /* Mask all interrupts */ csrw CSR_SIE, zero csrw CSR_SIP, zero |