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nipzunipzu
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‎.gitignore

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/build/
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/kernel.bin
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/dump.txt
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/out.txt
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/docs/.obsidian/

‎.vscode/settings.json

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{
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"rust-analyzer.cargo.target": "riscv64imac-unknown-none-elf",
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"rust-analyzer.cargo.allTargets": false
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}

‎booting.md

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- read fdt to determine usable memory
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- create page allocation structure
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- create kernel global data? ((num of) harts, ptr to scheduling & allocation)
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- maybe just use registers
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- create scheduling structure
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- create memory map structures
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- init program setup (create descriptor, insert to scheduler, memory map)
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- create per-thread descriptors
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- set trap handlers
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- wake up all threads
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sloader:
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- read fdt
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- set up memory allocation (needs fdt)
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- set up scheduling?
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- set up global page
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- set up hart pages
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- set up exception and interrupt handling (needs fdt)
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- set up uloader device map from fdt (without kernel)
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- set up uloader exe and stack memory by mapping (?)
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(hacky) act as a user prgoram and perform syscalls to set up uloader program
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(hacky) "become" uloader
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- jump to kernel code that returns to executor?

‎design.md

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### Per executor:
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- kernel scratch
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- executor info
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- scheduler entry
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- futex stuff??
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- virtual memory stuff
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- capabilities / handles / resources
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### Requirements:
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- rv64ia
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- S-mode
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- rv39?, rv48?
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### High Level States:
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- wfi / sleep / program that sleeps???
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- scheduling
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- executing user program
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- handling system call
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- running in U-mode
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### System Calls:
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- yield
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- map memory
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- start executor
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- wake
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- stop executor
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- system info: global read-only page
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- terminate
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### resources:
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- address space
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- executor
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- are mapped as pages into user vmem with U-mode set
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- address space for executor cannot be changed
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### Procedures:
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- virt to phys
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- phys to virt
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- zero page
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- map page(s)
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### Userspace pages (lowmem)
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- normal memory (RSW = 0b00) (U=1)
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- device memory (RSW = 0b01) (U=1)
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- executor page (RSW = 0b10) (U=0)
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- vas page (RSW = 0B11) (U=0)
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user mode: sscratch = S satp?,
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supervisor mode: sscratch =
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user mode:
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- S-satp
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- P-page
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kernel mode:
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- U-satp
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- P-page
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- set queue
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- park
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- read queue
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- unpark?
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park_and_op
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unpark
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park_and_op:
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1. *thread_page.parked bit = true // still have executing bit set
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2. op
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unpark:
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1. *thread_page.parked bit = false
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2. if not executing, move to scheduler queue
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scheduler queue can have multiples?
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park_and_swap
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unpark
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park_if(addr, expected):
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if !validate(addr):
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return ERR_ADDR
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set_parked(true)
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v = load_u_virt(addr)
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if v != expected:
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set_parked(false)
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return ERR_VAL
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yield()
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unpark(id):
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state = load_state(id)
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if parked(state) && executing(state):
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if parked(state) && !executing(state):
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### memory maps
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- reference count in invalid PTE / allocator array node
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-
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### page alloc and scheduling stuff on same page = Global Page
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### scheduling
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- just a global FIFO for now idk
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- thread local spmc?
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### page allocation
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- initially support only FLATMEM
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- maybe add support for SPARSEMEM (binary search)
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- see longqueue, mpmc
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- types of kernel pages:
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1. executor
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2. mm (root / other)
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3. hart-local
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### kernel register convention
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- x3/gp = global kernel page
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- x4/tp = hart page
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- x8 = current executor
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- x3 = kernel satp
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- x4 = page allocator
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### kernel hart page (x4/tp)
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0x000:0x008 = mcs_lock_next
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0x200:0x208 = mcs_lock_held
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### global kernel page (x3/gp)
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0x000:0x008 = page_alloc_head
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0x200:0x208 = page_alloc_tail
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0x400:0x408 = sched_mcs_lock
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0x600:0x608 = sched_head
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0x608:0x610 = sched_tail
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### executor state page
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0x00:0x08 = pc | kernel hart-local
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0x08:0x10 = x1
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0x10:0x18 = x2
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0x18:0x20 = x3
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0x20:0x28 = x4
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0x28:0x30 = x5
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0x30:0x38 = x6
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0x38:0x40 = x7
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0x40:0x48 = x8
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0x48:0x50 = x9
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0x50:0x58 = x10
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0x58:0x60 = x11
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0x60:0x68 = x12
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0x68:0x70 = x13
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0x70:0x78 = x14
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0x78:0x80 = x15
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0x80:0x88 = x16
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0x88:0x90 = x17
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0x90:0x98 = x18
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0x98:0xA0 = x19
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0xA0:0xA8 = x20
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0xA8:0xB0 = x21
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0xB0:0xB8 = x22
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0xB8:0xC0 = x23
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0xC0:0xC8 = x24
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0xC8:0xD0 = x25
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0xD0:0xD8 = x26
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0xD8:0xE0 = x27
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0xE0:0xE8 = x28
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0xE8:0xF0 = x29
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0xF8:0xF0 = x30
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0xF0:0x100 = x31
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0x100:0x108 = ptr to next to schedule
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0x110:0x118 = satp
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0x118:0x120 = ptr to vas
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0x120:0x128 = current hart page
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0x200:0x208 = state (running / terminated / waiting)
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0x400:0x408 = refcount
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0x800:0x808 = locked

‎docs/Kernel common.md

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## kernel register convention
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- x3/gp = global kernel page
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- x4/tp = hart page
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- x8/fp = current executor
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- aX registers used for syscall args/res
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- tX registers can be used, macros can garble
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-- x3 = kernel satp
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-- x4 = page allocator
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## Kernel pages
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# TODO: move mcs_lock state from hart to executor (remove hart page completely?)
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### kernel hart page (x4/tp)
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`0x000:0x008` = mcs_lock_next
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`0x200:0x208` = mcs_lock_held
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### global kernel page (x3/gp)
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`0x000:0x008` = page_alloc_head
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`0x200:0x208` = page_alloc_tail
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`0x400:0x408` = sched_mcs_lock
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`0x600:0x608` = sched_head
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`0x608:0x610` = sched_tail
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`0x700:0x708` = kernel_satp
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### executor state page
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`0x000:0x008` = pc | kernel hart-local
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`0x008:0x010` = x1
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`0x010:0x018` = x2
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`0x018:0x020` = x3
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`0x020:0x028` = x4
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`0x028:0x030` = x5
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`0x030:0x038` = x6
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`0x038:0x040` = x7
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`0x040:0x048` = x8
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`0x048:0x050` = x9
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`0x050:0x058` = x10
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`0x058:0x060` = x11
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`0x060:0x068` = x12
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`0x068:0x070` = x13
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`0x070:0x078` = x14
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`0x078:0x080` = x15
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`0x080:0x088` = x16
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`0x088:0x090` = x17
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`0x090:0x098` = x18
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`0x098:0x0A0` = x19
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`0x0A0:0x0A8` = x20
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`0x0A8:0x0B0` = x21
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`0x0B0:0x0B8` = x22
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`0x0B8:0x0C0` = x23
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`0x0C0:0x0C8` = x24
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`0x0C8:0x0D0` = x25
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`0x0D0:0x0D8` = x26
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`0x0D8:0x0E0` = x27
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`0x0E0:0x0E8` = x28
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`0x0E8:0x0F0` = x29
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`0x0F0:0x0F8` = x30
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`0x0F8:0x100` = x31
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`0x100:0x108` = ptr to next to schedule
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`0x110:0x118` = satp?
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`0x118:0x120` = ptr to vas?
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`0x120:0x128` = current hart page
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`0x200:0x208` = state (park) (running / terminated / waiting?)
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`0x400:0x408` = refcount?
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`0x800:0x808` = locked?

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