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include/acpi.h

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 1#ifndef FURIX_ACPI_H
 2#define FURIX_ACPI_H
 3
 4#include <efi.h>
 5#include <types.h>
 6
 7#define ACPI_MAX_APIC_IDS 256
 8
 9struct acpi_madt_info {
10  uint32_t cpu_count;
11  uint32_t ioapic_count;
12
13  /*
14   * firmware-reported processor IDs, which for a MADT using x2APIC entries are
15   * 32-bit and need not fit in a byte. kept as uint32_t rather than narrowed,
16   * because a truncated ID silently retargets an INIT/SIPI at the wrong CPU,
17   * which presents as an AP that never boots.
18   */
19  uint32_t apic_ids[ACPI_MAX_APIC_IDS];
20
21  /*
22   * dense 0..cpu_count-1 index into the per-CPU array, parallel to apic_ids.
23   *
24   * needed because x2APIC IDs may exceed the number of per-CPU slots we
25   * reserve, so the ID itself cannot be used as an array index. the BSP picks
26   * the slot and the trampoline is patched with it.
27   */
28  uint8_t slots[ACPI_MAX_APIC_IDS];
29};
30
31/* locate the RSDP via the UEFI config table and enumerate the MADT */
32bool acpi_madt_parse(const EFI_SYSTEM_TABLE *st, struct acpi_madt_info *out);
33
34/*
35 * number of processors the BSP must start, i.e. every MADT CPU except itself.
36 *
37 * a helper rather than open-coded `cpu_count - 1`: if the MADT lists no
38 * enabled local APIC at all, the subtraction wraps to UINT32_MAX and the
39 * bring-up loop spins looking for four billion processors.
40 */
41uint32_t acpi_madt_ap_count(const struct acpi_madt_info *madt);
42
43#endif /* FURIX_ACPI_H */