Robert Allan James
accd79fc70
Punch list §25 item 0.3 NOT complete. - Added `starkernel/fdt.h` and `fdt.c` for minimal read-only devicetree parsing: sufficient for boot-time lookups such as `timebase-frequency`. - Bootloader now captures the devicetree blob (DTB) from `EFI_DTB_TABLE_GUID` into `BootInfo::dtb`. - RISC-V timer subsystem now uses the `time` CSR as the primary timestamp source, abandoning the hardcoded `cycle` frequency assumption. - Timer rate is read from `timebase-frequency` in the DTB when accessible; otherwise, a fallback value is used with a RELATIVE trust level. - Integrated the SBI TIME extension for one-shot timer deadlines, ensuring re-arming occurs after each tick to avoid missing heartbeats. Verified: riscv64 builds clean, boots to the ok> prompt with no regression; `riscv64/timer.c` reports accurate frequencies on QEMU's default firmware. Signed-off-by: Robert Allan James <robert.allan.james@gmail.com>
40 lines
1.8 KiB
C
40 lines
1.8 KiB
C
/*
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* boot_info_offsets.h — fixed byte offsets of BootInfo fields
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*
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* Read by kernel_entry.S (assembly) AND verified by _Static_assert in
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* uefi_loader.c. Both uses share this header; only #define directives
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* are used so the file is valid for the C preprocessor AND the GAS
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* preprocessor (which runs on .S files compiled via CC).
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*
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* If you change the BootInfo struct layout in uefi.h, update the
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* constants below AND re-check the _Static_asserts (search BOOT_INFO_OFFSETS).
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*
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* BootInfo layout (64-bit, natural alignment):
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* 0: memory_map ptr (8)
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* 8: memory_map_size u64 (8)
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* 16: memory_map_descriptor_size u64 (8)
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* 24: runtime_services ptr (8)
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* 32: acpi_table ptr (8)
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* 40: dtb ptr (8)
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* 48: framebuffer FramebufferInfo (32)
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* .base ptr (8)
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* .size u64 (8)
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* .width u32 (4)
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* .height u32 (4)
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* .pixels_per_scanline u32 (4)
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* .pixel_format u32 (4)
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* 80: uefi_boot_services_exited u8 (1)
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* 81: [7 bytes padding]
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* 88: kernel_stack_base ptr (8) ← BOOT_INFO_KERNEL_STACK_BASE_OFFSET
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* 96: kernel_stack_size u64 (8) ← BOOT_INFO_KERNEL_STACK_SIZE_OFFSET
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* 104: args KernelArgs
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*
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* 2026-08-03, punch-list item 0.3: `dtb` inserted at 40, shifting everything
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* below it by 8. The _Static_asserts in uefi_loader.c caught the stale
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* constants immediately — that is what they are for; do not silence them by
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* moving a field, fix the offsets.
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*/
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#define BOOT_INFO_KERNEL_STACK_BASE_OFFSET 88
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#define BOOT_INFO_KERNEL_STACK_SIZE_OFFSET 96
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