mirror of
https://github.com/JannisHeydemann/BoredOS.git
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b85bb900e6
* Flush PS/2 Devices on boot to avoid Locking dependent on the out buffer on real hardware / emulated PS2 over USB Removed Slow and Unnessisarty flipping causing kconsole write slowdowns consequently speeding up the boot process * sod wc * ignoring dynamically created objects, added make run rule which will automatically detect the platform and then use the correct platform rule * ACPI Power Shutdown
36 lines
1.4 KiB
Markdown
36 lines
1.4 KiB
Markdown
<div align="center">
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<h1>ACPI</h1>
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<p><em>ACPI Power Interface</em></p>
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</div>
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ACPI Subsystem
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BoredOS implements an ACPI subsystem which manages power state transitions.
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The implementation lives
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in `src/acpi/`
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---
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### Startup and Table Discovery
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The first thing that ACPI does at boot time is to locate the RSDP.This can simply be requested fromlimine.
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If the pointer is not present or the pointer is not valid we panic!It is a hardware requirement
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If this is not present then we also check a checksum if that fails then the RSDP is also not valid and we panic
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XSDT vs RSDT Fallback
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When the RSDP specifies aRevision of 2 or greater, and we have a valid XSDT Address then we should try and use the XSDT instead,otherwise we use the RSDT.This is automatically abstracted by `acpi_get_sdt()`
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---
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### Shutdown and Power Off
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This works by writing an appropriate value to PM1 Control Block register, and will prompt hardware to move into S5 power state.
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### Performing the power off
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Once the sleep types are identified and so on, this will continue as follows
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On hardware that actually obeys ACPI standards this process should only perform step 1, and your machine should be turned off. To try and handle virtual machines or emulators that are known to fail at step 1,
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we send the virtual machine interrupts second in case writing bytes makes our hardware think it is acting up and we do not wish to cause an unnecessary interrupt
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