refactor(adapter-riscv): split kmain into boot/, devices/ modules

kmain is now 20 lines — six function calls:

  hardware::init        → BSS, MMU, traps, timer, PLIC, kernel
  loader::load_init     → read init.elf, create process, map ELF
  loader::load_server   → read server ELF, create process, map ELF
  storage_setup         → VirtIO block re-init, shared buffer, phys-info
  gpu_setup             → VirtIO GPU init, framebuffer alloc, phys-info
  caps::grant_all       → endpoints, capability grants

New modules:
  boot/hardware.rs   — hardware init (BSS, MMU, traps, kernel)
  boot/loader.rs     — ELF loading, thread setup, enter_userspace
  boot/caps.rs       — endpoint creation, capability grants
  devices/storage_setup.rs — VirtIO block for storage server
  devices/gpu_setup.rs     — VirtIO GPU for display server

All unsafe contained in hw/, mmu/, trap/. Boot and device
modules call safe wrappers.

crates/adapter-riscv/src/boot/caps.rs

@@ -0,0 +1,50 @@
+use crate::hw::uart::Uart;
+use crate::kernel_ref;
+use types::id::ProcessId;
+
+pub fn grant_all(
+    uart: &Uart,
+    init_pid: ProcessId,
+    storage_pid: ProcessId,
+    display_pid: ProcessId,
+) {
+    let all_perms = types::permission::PermissionSet::empty()
+        .with(types::permission::Permission::Read)
+        .with(types::permission::Permission::Write)
+        .with(types::permission::Permission::Execute)
+        .with(types::permission::Permission::Delegate);
+
+    let ipc_perms = types::permission::PermissionSet::empty()
+        .with(types::permission::Permission::Read)
+        .with(types::permission::Permission::Execute);
+
+    // Storage endpoint
+    let storage_ep = kernel_ref().create_endpoint()
+        .unwrap_or_else(|_| crate::halt(uart, "storage endpoint failed"));
+
+    // Init: slot 0 = ProcessCreate (from boot), slot 1 = Process(storage), slot 2 = Endpoint(storage)
+    kernel_ref().grant_capability(init_pid, domain::resource::Resource::Process(storage_pid), all_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+    kernel_ref().grant_capability(init_pid, domain::resource::Resource::Endpoint(storage_ep), all_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+
+    // Storage: slot 0 = Endpoint
+    kernel_ref().grant_capability(storage_pid, domain::resource::Resource::Endpoint(storage_ep), ipc_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+
+    // Display endpoint
+    let display_ep = kernel_ref().create_endpoint()
+        .unwrap_or_else(|_| crate::halt(uart, "display endpoint failed"));
+
+    // Display: slot 0 = Endpoint
+    kernel_ref().grant_capability(display_pid, domain::resource::Resource::Endpoint(display_ep), ipc_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+
+    // Init: slot 3 = Endpoint(display), slot 4 = Process(display)
+    kernel_ref().grant_capability(init_pid, domain::resource::Resource::Endpoint(display_ep), all_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+    kernel_ref().grant_capability(init_pid, domain::resource::Resource::Process(display_pid), all_perms)
+        .unwrap_or_else(|_| crate::halt(uart, "grant failed"));
+
+    uart.write_str("k-os: capabilities granted\n");
+}

crates/adapter-riscv/src/boot/hardware.rs

@@ -0,0 +1,52 @@
+use crate::hw::uart::Uart;
+use crate::hw::virtio_blk::VirtioBlk;
+use crate::{board, kernel_cell::KernelCell, mmu, platform, trap, KERNEL};
+
+unsafe extern "C" {
+    static _bss_start: u8;
+    static _bss_end: u8;
+    static _heap_start: u8;
+}
+
+pub fn init(uart: &Uart) -> &'static mut mmu::PageTable {
+    zero_bss();
+
+    let heap_start = unsafe { &_heap_start as *const u8 as usize };
+    mmu::init_allocator(heap_start);
+    let kernel_pt = mmu::init_kernel_page_table();
+    mmu::activate(kernel_pt);
+    uart.write_str("k-os: MMU enabled (Sv39)\n");
+
+    trap::init();
+    crate::hw::timer::init();
+    crate::hw::plic::Plic::init();
+    uart.write_str("k-os: traps and timer initialized\n");
+
+    let riscv_platform = platform::RiscVPlatform::new(kernel_pt as *const mmu::PageTable as usize);
+    let pool = domain::memory::page_pool::PagePool::new(
+        types::address::PhysicalAddress::from_raw(board::USER_POOL_BASE),
+        board::USER_POOL_PAGES,
+    );
+    KERNEL.init(kernel::Kernel::new(riscv_platform, pool));
+
+    kernel_pt
+}
+
+pub fn probe_block_device(uart: &Uart) -> Option<VirtioBlk> {
+    let blk = VirtioBlk::probe();
+    if blk.is_some() {
+        uart.write_str("k-os: VirtIO block device found\n");
+    } else {
+        uart.write_str("k-os: no block device\n");
+    }
+    blk
+}
+
+fn zero_bss() {
+    unsafe {
+        let start = &_bss_start as *const u8 as *mut u8;
+        let end = &_bss_end as *const u8 as *mut u8;
+        let len = end as usize - start as usize;
+        core::ptr::write_bytes(start, 0, len);
+    }
+}

crates/adapter-riscv/src/boot/loader.rs

@@ -0,0 +1,173 @@
+use crate::hw::uart::Uart;
+use crate::hw::virtio_blk::VirtioBlk;
+use crate::{board, boot_fs, kernel_ref, mmu};
+use types::id::{ProcessId, ThreadId};
+
+const USER_VA_BASE: usize = 0x10000;
+const MAX_FILE_SIZE: usize = 64 * 1024;
+
+pub struct LoadedProcess {
+    pub pid: ProcessId,
+    pub entry: usize,
+}
+
+pub fn load_init(
+    uart: &Uart,
+    blk: &mut VirtioBlk,
+    kernel_pt: &mmu::PageTable,
+) -> (LoadedProcess, ThreadId) {
+    let (pid, tid) = kernel_ref()
+        .boot(types::bounded::Priority::DEFAULT, types::time::TimeSlice::DEFAULT)
+        .unwrap_or_else(|_| crate::halt(uart, "boot failed"));
+
+    let entry = load_elf(blk, kernel_pt, pid, b"init.elf");
+    if entry == 0 { crate::halt(uart, "init.elf not found"); }
+    setup_thread(tid, entry);
+    uart.write_str("k-os: init loaded\n");
+
+    (LoadedProcess { pid, entry }, tid)
+}
+
+pub fn load_server(
+    uart: &Uart,
+    blk: &mut VirtioBlk,
+    kernel_pt: &mmu::PageTable,
+    filename: &[u8],
+    label: &str,
+) -> LoadedProcess {
+    let pid = kernel_ref().create_process_internal()
+        .unwrap_or_else(|| crate::halt(uart, "process create failed"));
+    let entry = load_elf(blk, kernel_pt, pid, filename);
+    if entry == 0 { crate::halt(uart, "elf not found"); }
+    let tid = kernel_ref().spawn_thread_internal(pid)
+        .unwrap_or_else(|| crate::halt(uart, "thread spawn failed"));
+    setup_thread(tid, entry);
+    uart.write_str("k-os: ");
+    uart.write_str(label);
+    uart.write_str(" loaded\n");
+
+    LoadedProcess { pid, entry }
+}
+
+pub fn enter_userspace(pid: ProcessId, entry: usize, shared_buf_va: usize) -> ! {
+    let kern = kernel_ref();
+    let pt_addr = kern.platform_mut().page_table_for(pid);
+    if pt_addr != 0 {
+        mmu::activate(unsafe { &*(pt_addr as *const mmu::PageTable) });
+    }
+
+    let kernel_sp: usize;
+    unsafe { core::arch::asm!("mv {0}, sp", out(reg) kernel_sp) };
+    crate::trap::set_kernel_stack(kernel_sp);
+
+    unsafe {
+        core::arch::asm!(
+            "csrc sstatus, {spp}",
+            "csrs sstatus, {spie}",
+            "csrw sepc, {entry}",
+            "mv sp, {stack}",
+            "mv a0, {arg}",
+            "sret",
+            spp = in(reg) 1usize << 8,
+            spie = in(reg) 1usize << 5,
+            entry = in(reg) entry,
+            stack = in(reg) USER_VA_BASE,
+            arg = in(reg) shared_buf_va,
+            options(noreturn),
+        );
+    }
+}
+
+fn setup_thread(tid: ThreadId, entry: usize) {
+    if let Some(ctx) = kernel_ref().thread_context_mut(tid) {
+        ctx.set_pc(entry);
+        ctx.registers_mut()[2] = USER_VA_BASE;
+        ctx.set_status(1 << 5);
+    }
+}
+
+fn load_elf(
+    blk: &mut VirtioBlk,
+    kernel_pt: &mmu::PageTable,
+    pid: ProcessId,
+    filename: &[u8],
+) -> usize {
+    let buf_base = mmu::allocator::alloc_zeroed_page();
+    let file_pages = MAX_FILE_SIZE / 4096;
+    for _ in 1..file_pages {
+        mmu::allocator::alloc_zeroed_page();
+    }
+    let buf = unsafe { core::slice::from_raw_parts_mut(buf_base as *mut u8, MAX_FILE_SIZE) };
+
+    let file_size = boot_fs::read_file_from_disk(blk, filename, buf).unwrap_or(0);
+    if file_size == 0 { return 0; }
+
+    let elf_info = match elf::parse(&buf[..file_size]) {
+        Ok(info) => info,
+        Err(_) => return 0,
+    };
+
+    let user_pt = mmu::create_user_page_table(
+        kernel_pt,
+        types::address::PhysicalAddress::from_raw(0),
+        0,
+        types::address::VirtualAddress::from_raw(USER_VA_BASE),
+    );
+
+    for segment in elf_info.segments() {
+        let page_start = segment.vaddr & !0xFFF;
+        let offset_in_page = segment.vaddr & 0xFFF;
+        let total_size = offset_in_page + segment.mem_size;
+        let seg_pages = (total_size + 4095) / 4096;
+
+        for p in 0..seg_pages {
+            let page = mmu::allocator::alloc_zeroed_page();
+            let page_va = page_start + p * 4096;
+            let seg_file_start = if p == 0 { 0 } else { p * 4096 - offset_in_page };
+            let dest_off = if p == 0 { offset_in_page } else { 0 };
+            let copy_len = if seg_file_start < segment.file_size {
+                (segment.file_size - seg_file_start).min(4096 - dest_off)
+            } else { 0 };
+
+            if copy_len > 0 {
+                let src = segment.file_offset + seg_file_start;
+                if src + copy_len <= file_size {
+                    unsafe {
+                        core::ptr::copy_nonoverlapping(
+                            buf.as_ptr().add(src),
+                            (page as *mut u8).add(dest_off),
+                            copy_len,
+                        );
+                    }
+                }
+            }
+
+            let flags = if segment.flags.execute {
+                mmu::Sv39Flags::user_rx()
+            } else if segment.flags.write {
+                mmu::Sv39Flags::user_rw()
+            } else {
+                mmu::Sv39Flags::user_rx()
+            };
+            mmu::map(user_pt, mmu::Mapping {
+                va: types::address::VirtualAddress::from_raw(page_va),
+                pa: types::address::PhysicalAddress::from_raw(page),
+                pages: 1,
+                flags,
+            });
+        }
+    }
+
+    for i in 0..4usize {
+        let sp = mmu::allocator::alloc_zeroed_page();
+        mmu::map(user_pt, mmu::Mapping {
+            va: types::address::VirtualAddress::from_raw(USER_VA_BASE - (4 - i) * 4096),
+            pa: types::address::PhysicalAddress::from_raw(sp),
+            pages: 1,
+            flags: mmu::Sv39Flags::user_rw(),
+        });
+    }
+
+    kernel_ref().platform_mut().set_page_table(pid, user_pt as *const mmu::PageTable as usize);
+    elf_info.entry_point
+}

crates/adapter-riscv/src/boot/mod.rs

@@ -0,0 +1,3 @@
+pub mod caps;
+pub mod hardware;
+pub mod loader;