mirror of
https://github.com/lupyuen/nuttx-ox64.git
synced 2025-01-12 20:58:31 +08:00
Update doc
This commit is contained in:
parent
364ad10cac
commit
4880da4fe3
1 changed files with 102 additions and 46 deletions
148
README.md
148
README.md
|
|
@ -2650,55 +2650,46 @@ _How does a NuttX App make a System Call to NuttX Kernel?_
|
|||
|
||||
Our NuttX App calls `write`, which is a Proxy Version...
|
||||
|
||||
From nuttx/syscall/proxies/PROXY_write.c
|
||||
|
||||
```c
|
||||
// From nuttx/syscall/proxies/PROXY_write.c
|
||||
/* Auto-generated write proxy file -- do not edit */
|
||||
|
||||
#include <nuttx/config.h>
|
||||
#include <unistd.h>
|
||||
#include <syscall.h>
|
||||
|
||||
ssize_t write(int parm1, FAR const void * parm2, size_t parm3)
|
||||
{
|
||||
ssize_t write(int parm1, FAR const void * parm2, size_t parm3) {
|
||||
return (ssize_t)sys_call3((unsigned int)SYS_write, (uintptr_t)parm1, (uintptr_t)parm2, (uintptr_t)parm3);
|
||||
}
|
||||
```
|
||||
Proxy for `write` calls...
|
||||
|
||||
[sys_call3](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/include/syscall.h), which makes an `ecall` to NuttX Kernel...
|
||||
Proxy for `write` calls [sys_call3](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/include/syscall.h), which makes an `ecall` to NuttX Kernel...
|
||||
|
||||
```c
|
||||
// Make an `ecall` to NuttX Kernel
|
||||
static inline uintptr_t sys_call3(unsigned int nbr, uintptr_t parm1,
|
||||
uintptr_t parm2, uintptr_t parm3)
|
||||
{
|
||||
uintptr_t parm2, uintptr_t parm3) {
|
||||
register long r0 asm("a0") = (long)(nbr);
|
||||
register long r1 asm("a1") = (long)(parm1);
|
||||
register long r2 asm("a2") = (long)(parm2);
|
||||
register long r3 asm("a3") = (long)(parm3);
|
||||
|
||||
asm volatile
|
||||
(
|
||||
"ecall"
|
||||
:: "r"(r0), "r"(r1), "r"(r2), "r"(r3)
|
||||
: "memory"
|
||||
);
|
||||
|
||||
asm volatile("nop" : "=r"(r0));
|
||||
|
||||
return r0;
|
||||
}
|
||||
```
|
||||
|
||||
TODO: Why `nop`?
|
||||
|
||||
Here's how it works...
|
||||
|
||||
|
||||
|
||||
List of proxies...
|
||||
We can see the list of proxies in the RISC-V Disassembly of the NuttX Apps...
|
||||
|
||||
```bash
|
||||
## Hello App
|
||||
→ grep PROXY hello.S
|
||||
PROXY__assert.c
|
||||
PROXY__exit.c
|
||||
|
|
@ -2713,6 +2704,7 @@ PROXY_sem_trywait.c
|
|||
PROXY_task_setcancelstate.c
|
||||
PROXY_write.c
|
||||
|
||||
## NuttX Shell NSH
|
||||
→ grep PROXY init.S
|
||||
PROXY__assert.c
|
||||
PROXY__exit.c
|
||||
|
|
@ -2764,46 +2756,58 @@ PROXY_waitpid.c
|
|||
|
||||
# Kernel Handles App Call
|
||||
|
||||
TODO
|
||||
_Our App makes an ecall to jump to NuttX Kernel..._
|
||||
|
||||
From nuttx/syscall/stubs/STUB_write.c
|
||||
_What happens on the other side?_
|
||||
|
||||
Remember the Proxy Function from earlier? Now we do the exact opposite in our __Stub Function__ (that runs in the Kernel)...
|
||||
|
||||
```c
|
||||
// From nuttx/syscall/stubs/STUB_write.c
|
||||
/* Auto-generated write stub file -- do not edit */
|
||||
|
||||
#include <nuttx/config.h>
|
||||
#include <stdint.h>
|
||||
#include <unistd.h>
|
||||
|
||||
uintptr_t STUB_write(int nbr, uintptr_t parm1, uintptr_t parm2, uintptr_t parm3)
|
||||
{
|
||||
uintptr_t STUB_write(int nbr, uintptr_t parm1, uintptr_t parm2, uintptr_t parm3) {
|
||||
return (uintptr_t)write((int)parm1, (FAR const void *)parm2, (size_t)parm3);
|
||||
}
|
||||
```
|
||||
|
||||
TODO: Handle IRQ 8 (RISCV_IRQ_ECALLU)
|
||||
To handle IRQ 8 (RISCV_IRQ_ECALLU), NuttX does...
|
||||
|
||||
[Attach RISCV_IRQ_ECALLU](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_exception.c#L114-L119), which calls...
|
||||
- [Attach RISCV_IRQ_ECALLU](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_exception.c#L114-L119), which calls...
|
||||
|
||||
[riscv_swint](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L105-L537), which calls...
|
||||
- [riscv_swint](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L105-L537), which calls...
|
||||
|
||||
[dispatch_syscall](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L54-L100), which calls Kernel Function Stub and...
|
||||
- [dispatch_syscall](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L54-L100), which calls Kernel Function Stub and...
|
||||
|
||||
[sys_call2](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/supervisor/riscv_syscall.S#L49-L177) with A0=SYS_syscall_return (3), which calls...
|
||||
- [sys_call2](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/supervisor/riscv_syscall.S#L49-L177) with A0=SYS_syscall_return (3), which calls...
|
||||
|
||||
[riscv_perform_syscall](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/supervisor/riscv_perform_syscall.c#L36-L78), which calls...
|
||||
- [riscv_perform_syscall](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/supervisor/riscv_perform_syscall.c#L36-L78), which calls...
|
||||
|
||||
[riscv_swint](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L105-L537) with IRQ 0, to return from Syscall
|
||||
- [riscv_swint](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/src/common/riscv_swint.c#L105-L537) with IRQ 0, to return from Syscall
|
||||
|
||||
From [syscall_lookup.h](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/include/sys/syscall_lookup.h#L202)
|
||||
_How did we figure out that 63 is the System Call Number for "write"?_
|
||||
|
||||
OK this part gets tricky. Below is the Enum that defines all __System Call Numbers__: [syscall.h](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/include/sys/syscall.h#L55-L66) and [syscall_lookup.h](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/include/sys/syscall_lookup.h#L202)
|
||||
|
||||
```c
|
||||
SYSCALL_LOOKUP(write, 3)
|
||||
// System Call Enum sequentially assigns
|
||||
// all System Call Numbers (8 to 147-ish)
|
||||
enum {
|
||||
...
|
||||
SYSCALL_LOOKUP(close, 1)
|
||||
SYSCALL_LOOKUP(ioctl, 3)
|
||||
SYSCALL_LOOKUP(read, 3)
|
||||
SYSCALL_LOOKUP(write, 3)
|
||||
...
|
||||
};
|
||||
```
|
||||
|
||||
Which defines SYS_write in the [Syscall Enum](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/include/sys/syscall.h#L55-L66)
|
||||
But it's an Enum, __numbered sequentially__ from 8 to 147-ish. We won't actually see 63 in the NuttX Source Code.
|
||||
|
||||
From hello.S:
|
||||
When we look at the RISC-V Disassembly hello.S:
|
||||
|
||||
```text
|
||||
ssize_t write(int parm1, FAR const void * parm2, size_t parm3)
|
||||
|
|
@ -2823,9 +2827,7 @@ sys_call3():
|
|||
dd2: 03f00513 li a0,63
|
||||
```
|
||||
|
||||
Thus SYS_write = 63
|
||||
|
||||
Also from hello.S:
|
||||
We see that SYS_write = 63. Also from hello.S:
|
||||
|
||||
```text
|
||||
<2><66e7>: Abbrev Number: 6 (DW_TAG_enumerator)
|
||||
|
|
@ -2833,9 +2835,11 @@ Also from hello.S:
|
|||
<66ec> DW_AT_const_value : 63
|
||||
```
|
||||
|
||||
TODO: Enable CONFIG_DEBUG_SYSCALL_INFO: Build Setup > Debug Options > Syscall Debug Features > Syscall Warning / Error / Info
|
||||
_What happens when we run this?_
|
||||
|
||||
From [ECALL Log](https://gist.github.com/lupyuen/ce82b29c664b1d5898b6a59743310c17)
|
||||
In `make menuconfig`, enable CONFIG_DEBUG_SYSCALL_INFO: Build Setup > Debug Options > Syscall Debug Features > Syscall Warning / Error / Info
|
||||
|
||||
The [NuttX Log](https://gist.github.com/lupyuen/ce82b29c664b1d5898b6a59743310c17) shows the System Calls from NuttX App to NuttX Kernel...
|
||||
|
||||
```text
|
||||
riscv_dispatch_irq: irq=8
|
||||
|
|
@ -2866,23 +2870,75 @@ up_dump_register: SP: 000000005040bcb0 FP: 00000000802005c0 TP: 0000000000000000
|
|||
riscv_swint: SWInt Return: 1e
|
||||
```
|
||||
|
||||
Before Call:
|
||||
_What are the Register Values?_
|
||||
|
||||
A0=0x3f (SYS_write)
|
||||
Before System Call:
|
||||
|
||||
A1=1 (stdout)
|
||||
- A0 = 0x3f (SYS_write)
|
||||
|
||||
A2=0x8000ad00 (g_nshgreeting)
|
||||
- A1 = 1 (stdout)
|
||||
|
||||
A3=0x1e (length)
|
||||
- A2 = 0x8000ad00 (g_nshgreeting)
|
||||
|
||||
nbr=440 (Offset for the stub lookup table, [g_stublookup](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/syscall/syscall_stublookup.c#L80-L93))
|
||||
- A3 = 0x1e (length)
|
||||
|
||||
After Call:
|
||||
- nbr = 440 (Offset for the stub lookup table, [g_stublookup](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/syscall/syscall_stublookup.c#L80-L93))
|
||||
|
||||
A0=3 [(SYS_syscall_return)](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/include/syscall.h#L80-L87)
|
||||
After System Call:
|
||||
|
||||
Returns 0x1E = 30 chars, including [linefeeds before and after](https://github.com/lupyuen2/wip-pinephone-nuttx-apps/blob/ox64b/nshlib/nsh_parse.c#L292-L302)
|
||||
- A0 = 3 [(SYS_syscall_return)](https://github.com/lupyuen2/wip-pinephone-nuttx/blob/ox64b/arch/risc-v/include/syscall.h#L80-L87)
|
||||
|
||||
- Returns 0x1E = 30 chars, including [linefeeds before and after](https://github.com/lupyuen2/wip-pinephone-nuttx-apps/blob/ox64b/nshlib/nsh_parse.c#L292-L302)
|
||||
|
||||
# Kernel Starts a NuttX App
|
||||
|
||||
_Phew so NuttX Apps can call NuttX Kernel..._
|
||||
|
||||
_But how does NuttX Kernel start a NuttX App?_
|
||||
|
||||
Earlier we stepped through the __Boot Sequence__ for NuttX...
|
||||
|
||||
- [__"NuttX Boot Flow"__](https://lupyuen.github.io/articles/ox2#appendix-nuttx-boot-flow)
|
||||
|
||||
Right after that, [__NuttX Bringup (nx_bringup)__](https://github.com/apache/nuttx/blob/master/sched/init/nx_bringup.c#L373-L458) calls...
|
||||
|
||||
- [__Create Init Thread: nx_create_initthread__](https://github.com/apache/nuttx/blob/master/sched/init/nx_bringup.c#L330-L367) (to create the Init Thread), which calls...
|
||||
|
||||
- [__Start App: nx_start_application__](https://github.com/apache/nuttx/blob/master/sched/init/nx_bringup.c#L212C1-L302) (to start NuttX Shell), which calls...
|
||||
|
||||
- [__Exec Spawn: exec_spawn__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_exec.c#L183-L223) (to start the app), which calls...
|
||||
|
||||
- [__Exec Internal: exec_internal__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_exec.c#L42-L179) (to start the app), which calls...
|
||||
|
||||
- [__Load Module: load_module__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_loadmodule.c#L136-L225) (to load the app, see below) and...
|
||||
|
||||
[__Execute Module: exec_module__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_execmodule.c#L190-L450) (to execute the app)
|
||||
|
||||
To load a NuttX App module: [__load_module__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_loadmodule.c#L136-L225) calls...
|
||||
|
||||
- [__Load Absolute Module: load_absmodule__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_loadmodule.c#L83-L132) (to load an absolute path), which calls...
|
||||
|
||||
- [__Load Binary Format: binfmt_s.load__](https://github.com/apache/nuttx/blob/master/include/nuttx/binfmt/binfmt.h#L122-L148) (to load a binary module), which calls...
|
||||
|
||||
- [__ELF Loader: g_elfbinfmt__](https://github.com/apache/nuttx/blob/master/binfmt/elf.c#L84-L94) (to load the ELF File, see below)
|
||||
|
||||
To load the ELF File: [__ELF Loader g_elfbinfmt__](https://github.com/apache/nuttx/blob/master/binfmt/elf.c#L84-L94) calls...
|
||||
|
||||
- [__Load ELF Binary: elf_loadbinary__](https://github.com/apache/nuttx/blob/master/binfmt/elf.c#L225-L355) (to load the ELF Binary), which calls...
|
||||
|
||||
- [__Load ELF: elf_load__](https://github.com/apache/nuttx/blob/master/binfmt/libelf/libelf_load.c#L297-L445) (to load the ELF Binary), which calls...
|
||||
|
||||
- [__Allocate Address Env: elf_addrenv_alloc__](https://github.com/apache/nuttx/blob/master/binfmt/libelf/libelf_addrenv.c#L56-L178) (to allocate the Address Env), which calls...
|
||||
|
||||
- [__Create Address Env: up_addrenv_create__](https://github.com/apache/nuttx/blob/master/arch/risc-v/src/common/riscv_addrenv.c#L339-L490) (to create the Address Env), which calls...
|
||||
|
||||
(Also calls [__mmu_satp_reg__](https://github.com/apache/nuttx/blob/master/arch/risc-v/src/common/riscv_mmu.h#L152-L176) to set SATP Register)
|
||||
|
||||
- [__Create MMU Region: create_region__](https://github.com/apache/nuttx/blob/master/arch/risc-v/src/common/riscv_addrenv.c#L213-L310) (to create the MMU Region), which calls...
|
||||
|
||||
- [__Set MMU Page Table Entry: mmu_ln_setentry__](https://github.com/apache/nuttx/blob/master/arch/risc-v/src/common/riscv_mmu.c#L62-L109) (to populate the Page Table Entries)
|
||||
|
||||
There's plenty happening inside [__Execute Module: exec_module__](https://github.com/apache/nuttx/blob/master/binfmt/binfmt_execmodule.c#L190-L450). But we won't explore today.
|
||||
|
||||
# Documentation for Ox64 BL808
|
||||
|
||||
|
|
|
|||
Loading…
Reference in a new issue