refactor(x86_64): cleanup dependencies and initialization code

[AsakuraMizu]

Tracking issue: #25

Description

All changes are related to x86_64:

1. Remove static_assertions
2. Remove init_percpu (due to feat: add percpu axplat_crates#42 and Add custom per-CPU area support, clarify init process, fix initialization percpu#22, this function is useless now)
3. Replace lazyinit with spin
4. Simplify initialization code (GDT, IDT)
5. Remove PROTECTION_VIOLATION from page fault reserved error code
6. Fix in trap.s that exceptions #CP(21)/#VC(29)/#SX(30) should have error code pushed on stack

[Copilot]

Pull request overview

Refactors the x86_64 CPU initialization and trap-handling plumbing by replacing custom GDT/IDT wrappers with x86_64 crate primitives, updating segment selector usage across user entry/syscall paths, and adjusting low-level trap metadata (error-code vectors and #PF flag parsing). Also updates dependencies to align with the new implementation choices.

Changes:

• Replace custom GDT/IDT structs and lazyinit usage with x86_64::{GlobalDescriptorTable, InterruptDescriptorTable} plus spin::Lazy.
• Update user-space context setup and syscall MSR configuration to use new gdt::* selector constants.
• Fix trap handling details (additional error-code vectors; allow PROTECTION_VIOLATION bit in #PF error code parsing) and adjust crate dependencies accordingly.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
src/x86_64/uspace.rs	Switch user CS/SS selectors to gdt::* constants.
src/x86_64/syscall.rs	Use gdt::* selectors when configuring STAR.
src/x86_64/trap.S	Treat additional exception vectors as having CPU-pushed error codes.
src/x86_64/trap.rs	Update reserved-bit filtering for page-fault error codes.
src/x86_64/gdt.rs	Replace custom GDT with GlobalDescriptorTable and define selector constants.
src/x86_64/idt.rs	Replace custom IDT with InterruptDescriptorTable initialized via spin::Lazy.
src/x86_64/init.rs	Simplify trap init flow; remove helper exports/functions.
src/x86_64/mod.rs	Stop re-exporting removed/now-internal x86_64 structs/types.
src/x86_64/context.rs	Replace static_assertions size check with a const assert!.
Cargo.toml	Update x86_64-target deps (percpu/spin) and adjust x86_64 features; remove static_assertions/lazyinit.
Cargo.lock	Reflect dependency upgrades/removals (percpu/spin; remove lazyinit/static_assertions).

Comments suppressed due to low confidence (1)

src/x86_64/mod.rs:18

• The module no longer re-exports GdtStruct, IdtStruct, and TaskStateSegment. Since these were public exports, removing them is a breaking API change for external users that may have depended on axcpu::x86_64::{GdtStruct, IdtStruct, TaskStateSegment}. If the intent is to make these internal-only, consider providing a migration path (re-export replacements like gdt::{KCODE64,...}), or bumping the crate version to reflect the breaking change.

pub mod uspace;

pub use self::context::{ExtendedState, FxsaveArea, TaskContext, TrapFrame};

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[equation314]

I think we should merge #16 and release v0.3.0 first, and then consider this PR.

[AsakuraMizu]

I think we should merge #16 and release v0.3.0 first, and then consider this PR.

OK, so shall we set #25 as the "milestone" of 0.4.0?

[Copilot]

Pull request overview

Refactors the x86_64 backend initialization and dependencies by simplifying GDT/IDT setup, updating trap/exception handling details, and removing now-unneeded helper APIs/crates.

Changes:

• Replaced lazyinit/custom IDT wrapper with spin::Lazy and direct InterruptDescriptorTable initialization.
• Reworked GDT initialization to use x86_64::GlobalDescriptorTable and new selector constants (gdt::{KCODE64,KDATA,UCODE64,UDATA}).
• Fixed trap/exception stack layout for #CP/#VC/#SX and adjusted page-fault error-code validation to treat PROTECTION_VIOLATION as non-reserved.

Reviewed changes

Copilot reviewed 10 out of 11 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
src/x86_64/uspace.rs	Switches user CS/SS setup to new gdt::* selectors.
src/x86_64/trap.S	Ensures vectors 21/29/30 follow “CPU-pushed error code” convention.
src/x86_64/trap.rs	Updates #PF error-code reserved-bit filtering.
src/x86_64/syscall.rs	Uses new gdt::* selectors for STAR MSR configuration.
src/x86_64/mod.rs	Removes public re-exports related to GDT/IDT/TSS.
src/x86_64/init.rs	Simplifies trap init path and drops init_percpu helper.
src/x86_64/idt.rs	Rebuilds IDT initialization with spin::Lazy and handler address table.
src/x86_64/gdt.rs	Replaces custom GDT struct with GlobalDescriptorTable + per-CPU TSS/GDT init.
src/x86_64/context.rs	Replaces static_assertions with a const-size assertion.
Cargo.toml	Removes lazyinit/static_assertions, adds spin, adjusts x86_64 dependency features.
Cargo.lock	Updates lockfile to reflect dependency changes.

Comments suppressed due to low confidence (1)

src/x86_64/mod.rs:18

• This module previously re-exported GdtStruct, IdtStruct, and TaskStateSegment, but those public exports were removed. Since src/lib.rs re-exports x86_64::* on x86_64 targets, this is a public API breaking change for downstream users that imported these symbols from axcpu. If the break is intended, consider documenting it in the changelog / bumping the crate version accordingly, or providing a compatibility re-export (possibly deprecated) to ease migration.

pub mod uspace;

pub use self::context::{ExtendedState, FxsaveArea, TaskContext, TrapFrame};

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