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documentation/kernel/sysabi.md

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ported data from nerdcult.net wiki
2023-05-28 17:16:43 +00:00
# SysABI
Syscalls are a way for programms to communicate with the kernel.
To perform a syscall, you need to populate the following registers:
| Register | Value |
|----------|-----------------|
| rax | The syscalls ID |
| rdi | Argument 1 |
| rsi | Argument 2 |
| rdx | Argument 3 |
| rcx | Argument 4 |
---
The following calls should be implemented to some degree in noxos 1.0.
# Categories
## Files
updated sysabi
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
|--------|----------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|--------|------|-------------|--------|-------------|
| 0x0001 | `nx_fs_open` | Opens the file at the _len_ bytes long path _path_ and writes a file descriptor to the referenced file into _fd_ (which needs to be a pointer). | path | len | *fd | | status | Implemented |
| 0x0002 | `nx_fs_close` | Closes the file which is indicated by descriptor _fd_. This should always be called, otherwise the OS will have to unload files without knowledge of usage. | fd | | | | status | Implemented |
| 0x0003 | `nx_fs_read` | Reads at most _n_ bytes from a file given as descriptor _fd_ and at a specific position _offset_ into a given memory region _mem_. | fd | offset | mem | n | status | Implemented |
| 0x0004 | `nx_fs_write` | Writes _n_ bytes from a given memory region _mem_ into the file referenced by _fd_ at the given position _offset_, not inserting but either overwriting existing content or appending to the file. | fd | offset | mem | n | status | Implemented |
| 0x0005 | `nx_fs_delete` | Completely delete the file or folder at a given path _path_, which is _len_ bytes long. | path | len | | | status | Implemented |
| 0x0006 | `nx_fs_list` | List all files and/or directories at the _len_ bytes long path _path_ and write their NULL-separated names into _mem_. When _mem_ is NULL, _needed_mem_ (which needs to be a pointer to an 32-bit integer) is filled with the appropriate value. | path | len | mem | *needed_mem | status | Implemented |
| 0x0007 | `nx_fs_info` | Writes the information about the files attribute _attr_ into mem. Types of attributes are described below. | fd | attr | mem | | status | N/A |
ported data from nerdcult.net wiki
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**Note:** The _len_ argument of paths isn't used at the moment, rather than using _len_, _path_ needs to be Null-Terminated.
## Memory
updated sysabi
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
|--------|------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|------|-------|------|--------|-------------|
| 0x0101 | `nx_mem_alloc` | Maps _n_ 4KB pages to address _addr_. You can provide a bitmap of flags with the _flags_ argument. Which flags can be used, is described below. | addr | n | flags | | status | Implemented |
| 0x0102 | `nx_mem_free` | Unmaps _n_ 4KB pages at address _addr_. | addr | n | | | status | Implemented |
| 0x0103 | `nx_mem_label` | Gives a memory region a file descriptor, called a label, which can then be used for example for executing executable data in that memory region in a new process | addr | len | *fd | | status | N/A |
| 0x0104 | `nx_mem_unlabel` | Takes the file descriptor away from a memory region. | fd | | | | status | N/A |
ported data from nerdcult.net wiki
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## Processes
documented process configuration and driver syscalls
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
|--------|------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------|--------|----------|------|------|--------|--------|
| 0x0201 | `nx_proc_create` | Creates a new process with the configuration _conf_ (which format is described below) and writes its process id to _pid_. | *conf | *pid | | | status | N/A |
| 0x0202 | `nx_proc_signal_send` | Send the signal _signal_ to _pid_. See below for a list of signals. | pid | signal | | | status | N/A |
| 0x0203 | `nx_proc_signal_set_handler` | Sets a handler for the signal _signal_ in the current process. Not all signals can have a handler. Look at the list for more information. | signal | *handler | | | status | N/A |
| 0x0204 | `nx_proc_thread_create` | Spawns a new thread for the current process. The starting point is defined by _addr_. The threads' ID is written into _tid_. | addr | *tid | | | status | N/A |
| 0x0205 | `nx_proc_thread_start` | Starts the current processes' thread with thread id _tid_. | tid | | | | status | N/A |
| 0x0206 | `nx_proc_thread_pause` | Pauses the current processes' thread with thread id _tid_. | tid | | | | status | N/A |
| 0x0207 | `nx_proc_thread_kill` | Kills the current processes' thread with thread id _tid_. | tid | | | | status | N/A |
updated sysabi
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## Drivers
documented process configuration and driver syscalls
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
|--------|--------------------------------|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|------|------|-------|------|--------|--------|
| 0x0301 | `nx_drv_register` | Registers the executable at the _n_ bytes long _path_ as driver with the configuration _conf_. The format of the conf struct can be found below. | path | len | *conf | | status | N/A |
| 0x0302 | `nx_drv_create_command_buffer` | This has to be called from a driver. Registers _addr_ as command queue buffer with the length _len_, which has to be greater or equal 16384. If _addr_ is NULL or not aligned to 32 bytes or _len_ is less than 16384, the kernel will map a command queue buffer into the drivers address space, which is of length _len_ but at least 16384. The address to the registered buffer will be returned. | addr | len | | | addr | N/A |
| 0x0303 | `nx_drv_flush_command_buffer` | This has to be called from a driver. Flushes the command queue buffer at _addr_. | addr | | | | status | N/A |
ported data from nerdcult.net wiki
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## Kernel
documented kernel syscalls
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These syscalls can only be called from the kernel process.
ported data from nerdcult.net wiki
2023-05-28 17:16:43 +00:00
If another process calls them, they will just return without doing anything.
documented kernel syscalls
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| ID | Name | Description | Arg1 | Arg2 | Arg3 | Arg4 | Result | Status |
|--------|-----------------------------|------------------------------------------------------------------------------------------------------|------|------|------|------|--------|-------------|
| 0xFF01 | `nx_kernel_scheduler_start` | Starts the kernel scheduler. The current execution point will be the kernel processes' first thread. | | | | | | Implemented |
| 0xFF02 | `nx_kernel_panic` | Causes a kernel panic. With _msg_ as error message. | msg | | | | | Implemented |
ported data from nerdcult.net wiki
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---
## Appendixes
### Types of file attributes
| ID | Name | Description | Data Type | Status |
|-----|---------------|--------------------------------------------|-----------|--------|
| 0 | `permissions` | Who has what permission to access the file | uint16_t | N/A |
| 1 | `size` | The files size in bytes | uint64_t | N/A |
documented process configuration and driver syscalls
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---
ported data from nerdcult.net wiki
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### Memory mapping flags
| Bit | Name | Description |
|-----|-----------|-------------------------------------------|
| 0 | `write` | Enables write access to the mapped pages. |
| 1 | `no_exec` | Prevents execution of the mapped pages. |
updated sysabi
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documented process configuration and driver syscalls
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---
updated sysabi
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### Process configuration
documented process configuration and driver syscalls
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**header:**
| Length(bytes) | Name | Description |
|--------------------------|-----------------|--------------------------------------------------------------------------------|
| 0x01 | privilege_level | Specifies the privilege level the process runs on. (described below) |
| 0x80 | name | The processes' name (ascii). |
| 0x08 | executable | A file descriptor to the executable the process will be loaded from. |
| 0x04 | num_inherit_fds | The amount of file descriptors that will be inherited to the process. |
| 0x0F * `num_inherit_fds` | inherit_fds | The file descriptors that will be inherited to the process. (described below) |
**header.privilege_level:**
| Value | Name | Description |
|-------|-----------|-------------------------------------------------------------------------|
| 0 | as_parent | The new process will spawn with the same privilege level as its parent. |
| 1 | default | The new process will spawn with default user permissions. |
**header.inherit_fds:**
| Length(bytes) | Name | Description |
|---------------|-----------|--------------------------------------------------------------------------------|
| 0x08 | at_parent | The file descriptor, the parent process wants to inherit. |
| 0x08 | at_child | The file descriptor in the new child process. Same as `at_parent` if set to 0. |
updated sysabi
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### Process signals
- __SIGSTART__: starts the process
- __SIGPAUSE__: pauses the process
- __SIGKILL__: kills the process and destroys the processes data structures
- __SIGEXIT__: send by the kernel before stopping the process - handler implementation possible
- __SIGPFAULT__: sends when the process access memory it is not permitted to. Followed by SIGEXIT - handler implementation possible
- __SIGMATHAULT__: sends when the process does stuff like dividing by zero. Followed by SIGEXIT - handler implementation possible
documented process configuration and driver syscalls
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---
### Driver configuration
**header:**
| Length(bytes) | Name | Description |
|---------------|--------------------|------------------------------------------------------------------------------|
| 0x01 | transport_protocol | Specifies the protocol over which the driver communicates. (described below) |
| 0x02 | length | Specifies the length of the `specific_config` section. |
| `length` | specific_config | Configuration specific to the transport protocol. (described below) |
**header.transport_protocol:**
| Value | Name | Description |
|-------|--------|------------------------------------------------------------------------------------------|
| 0 | PCI(e) | The driver connects to devices on the _Peripheral Component Interconnect (express)_ Bus. |
| 1 | USB | The driver connects to devices on the _Universal Serial Bus_. |
| 2 | FS | The driver provides filesystem functionalities. |
**header.specific_config.pci:**
| Length(bytes) | Name | Description |
|-------------------------|----------------|---------------------------------------------------------------|
| 0x02 | num_vendor_ids | The amount of PCI vendor ids the driver can handle. |
| 0x02 | num_device_ids | The amount of PCI device ids the driver can handle. |
| 0x02 * `num_vendor_ids` | vendor_ids | An array containing all PCI vendor ids the driver can handle. |
| 0x02 * `num_device_ids` | device_ids | An array containing all PCI device ids the driver can handle. |
**header.specific_config.usb:**
| Length(bytes) | Name | Description |
|---------------|-------------|-----------------------------------------|
| 0x01 | min_version | The minimum required major USB version. |
**header.specific_config.fs:**
| Length(bytes) | Name | Description |
|---------------|----------|-------------------------------------------------------------------------|
| 0x0F | gpt_guid | The gpt GUID of the file system type that the driver handles. |
| 0x01 | mbr_type | The mbr partition type of the file system type that the driver handles. |