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.\" Copyright (c) 2023-2024 Ian Marco Moffett and the Osmora Team.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright notice,
.\" this list of conditions and the following disclaimer.
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in the
.\" documentation and/or other materials provided with the distribution.
.\" 3. Neither the name of Hyra nor the names of its
.\" contributors may be used to endorse or promote products derived from
.\" this software without specific prior written permission.
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
.\" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
.\" ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
.\" LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
.\" POSSIBILITY OF SUCH DAMAGE.
.Dd Mar 13 2024
.Dt ARCH 9
.Os Hyra
.Sh NAME
.Nm arch - hyra arch information
.Sh SYNOPSIS
.In sys/machdep.h
.In machine/cpu.h
.In machine/pmap.h
.Sh DESCRIPTION
NOTE: All examples will be for x86_64 but can be applied to others
Information about how Hyra and architectures work together. This
will describe headers and .c files that need to exist for all
architectures and things they should include. The
.Ft machine/cpu.h
file contains information about the CPU for the specific
architecture. Required structures in this header include the
.Ft cpu_info
struct which contains CPU specific fields.
Example
.Ft cpu_info
structure shown below:
.Bd -literal
struct cpu_info {
/* Per-arch fields */
void *pmap; /* Current pmap */
uint32_t id;
struct spinlock lock;
/* AMD64 */
...
};
.Ed
There will be some per-architecture fields that, for the sake
of keeping things tidy, should remain at the top of the struct.
These fields will be described below.
The
.Ft pmap
field points to the current virtual memory context
which shall be NULL if not used.
The
.Ft id
field simply identifies the CPU with a specific "ID".
The
.Ft lock
field is a spinlock to prevent race conditions
while accessing this structure. This must be acquired
when accessing a
.Ft cpu_info
instance.
There are also some common helper macros that shall
be implemented, these are described below.
The macro
.Ft this_cpu()
calls an internal function that fetches the
cpu_info structure for the current CPU.
The macro
.Ft get_bsp()
calls an internal function that fetches the
cpu_info structure for the BSP.
The macro
.Ft hint_spinwait()
hints the processor that it is currently
in a spin-wait loop. This greatly reduces the
processor’s power consumption and improves
the performance of the spin-wait loop.
The function these macros call must return a pointer
to a
.Ft cpu_info
structure.
In the
.Ft machine/pmap.h
header, should be a struct containing information
about the address space. This header MUST be implemented
or compiler errors will occur.
There also exists a
.Ft pcb
(Process Control Block) structure in the
.Ft machine/pcb.h
header which contains arch specific information per thread.
This structure must be implemented per arch, this structure shall be set up
by the machdep subsystem, specifically in the
.Ft processor_init_pcb()
routine.
The
.Ft processor_free_pcb()
routine shall also be implemented per arch to deallocate
resources when the thread is killed.
.Sh AUTHORS
.An Ian Moffett Aq Mt ian@osmora.org
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