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feat: allow for usage of passed dtb addr #482

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Merged
mkroening merged 1 commit into from
Sep 4, 2025
Merged

feat: allow for usage of passed dtb addr #482

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2 changes: 1 addition & 1 deletion src/arch/aarch64/console.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -16,7 +16,7 @@ fn stdout() -> SerialPort {
const SERIAL_PORT_ADDRESS: u32 = 0x09000000;

let dtb = unsafe {
Fdt::from_ptr(sptr::from_exposed_addr(super::DEVICE_TREE as usize))
Fdt::from_ptr(sptr::from_exposed_addr(super::get_dtb_addr() as usize))
.expect(".dtb file has invalid header")
};

Expand Down
26 changes: 16 additions & 10 deletions src/arch/aarch64/entry.s
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Original file line number Diff line number Diff line change
Expand Up @@ -5,17 +5,20 @@
.section .text

_linux: // Let's fake being linux! https://www.kernel.org/doc/Documentation/arm64/booting.txt
mov x0, #1 // code0: Do nothing here (no uefi)
b _start // code1: Branch to real stuff....
.quad 0 // text_offset: linux needs none, neither do we
nop // code0: Do nothing here (no uefi)
b _linux_start // code1: Branch to real stuff....
.quad 0 // text_offset: linux needs none, neither do we
.quad prog_size
.quad 2 // flags: 4k pagesize. might need adjustment. Page size currently undefined.
.quad 0 // res2: reserved
.quad 0 // res3: reserved
.quad 0 // res4: reserved
.long 0x644d5241 // magic: "ARMx64"
.long 0 // res5: header size for efi boot. Not needed.
.quad 2 // flags: 4k pagesize. might need adjustment. Page size currently undefined.
.quad 0 // res2: reserved
.quad 0 // res3: reserved
.quad 0 // res4: reserved
.long 0x644d5241 // magic: "ARMx64"
.long 0 // res5: header size for efi boot. Not needed.
.align 8
_linux_start:
adr x8, dtb_addr
str x0, [x8, 0]
_start:
// Only proceed on the boot core. Park it otherwise.
mrs x1, mpidr_el1
Expand Down Expand Up @@ -100,6 +103,7 @@ el_1_entry:
.global l2k_pgtable
.global l3_pgtable
.global L0mib_pgtable
.global dtb_addr

.align 12
l0_pgtable:
Expand Down Expand Up @@ -131,4 +135,6 @@ L14mib_pgtable:
L16mib_pgtable:
.space 512*8, 0
L18mib_pgtable:
.space 512*8, 0
.space 512*8, 0
dtb_addr:
.space 8, 0
11 changes: 8 additions & 3 deletions src/arch/aarch64/mod.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -30,6 +30,7 @@ unsafe extern "C" {
static mut l2k_pgtable: u64;
static mut l3_pgtable: u64;
static mut L0mib_pgtable: u64;
static mut dtb_addr: u64;
}

/// start address of the RAM at Qemu's virt emulation
Expand All @@ -52,9 +53,13 @@ pub unsafe fn get_memory(_memory_size: u64) -> u64 {
(ptr::addr_of_mut!(loader_end).expose_addr() as u64).align_up(LargePageSize::SIZE as u64)
}

pub unsafe fn get_dtb_addr() -> u64 {
unsafe { if dtb_addr != 0 { dtb_addr } else { DEVICE_TREE } }
}

pub fn find_kernel() -> &'static [u8] {
let dtb = unsafe {
Fdt::from_ptr(sptr::from_exposed_addr(DEVICE_TREE as usize))
Fdt::from_ptr(sptr::from_exposed_addr(get_dtb_addr() as usize))
.expect(".dtb file has invalid header")
};
let module_start = dtb
Expand Down Expand Up @@ -112,7 +117,7 @@ pub unsafe fn boot_kernel(kernel_info: LoadedKernel) -> ! {
} = kernel_info;

let dtb = unsafe {
Fdt::from_ptr(sptr::from_exposed_addr(DEVICE_TREE as usize))
Fdt::from_ptr(sptr::from_exposed_addr(get_dtb_addr() as usize))
.expect(".dtb file has invalid header")
};
let cpus = dtb.cpus().count();
Expand Down Expand Up @@ -217,7 +222,7 @@ pub unsafe fn boot_kernel(kernel_info: LoadedKernel) -> ! {
hardware_info: HardwareInfo {
phys_addr_range: ram_start..ram_start + ram_size,
serial_port_base: SerialPortBase::new(0x1000),
device_tree: core::num::NonZeroU64::new(DEVICE_TREE),
device_tree: unsafe { core::num::NonZeroU64::new(get_dtb_addr()) },
},
load_info,
platform_info: PlatformInfo::LinuxBoot,
Expand Down
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