[arm_compiler_v4/v5] define rt_packed as __packed

[cmbjxxiao]

拉取/合并请求描述：(PR description)

[

为什么提交这份PR (why to submit this PR)

使用MDK5编译器编译工程后，在运行find_valid_gpt函数时， 因sizeof (legacy_mbr)得出的长度未按1字节对齐而出现内存覆盖问题

你的解决方案是什么 (what is your solution)

1、当 __ARMCC_VERSION < 6010050 时定义 rt_packed 为 __packed
2、参考文档:
1）ARM Compiler toolchain Using the Compiler Version 5.01
https://developer.arm.com/documentation/dui0472/g/compiler-coding-practices/the---packed-qualifier-and-unaligned-data-access-in-c-and-c---code?lang=en
2）ARM Compiler toolchain Using the Compiler Version 4.1
https://developer.arm.com/documentation/dui0472/c/compiler-coding-practices/the---packed-qualifier-and-unaligned-data-access-in-c-and-c---code?lang=en
3）ARM Software Development Toolkit Reference Guide Version 2.50
https://developer.arm.com/documentation/dui0041/c/ARM-Compiler-Reference/Compiler-specific-features/Type-qualifiers?lang=en

请提供验证的bsp和config (provide the config and bsp)

• BSP:qemu-vexpress-a9

• .config:CONFIG_RT_USING_DFS=y,CONFIG_RT_USING_BLK=y,CONFIG_RT_BLK_PARTITION_EFI=y,CONFIG_BSP_USING_SDIO=y,CONFIG_BSP_USING_SDIO1=y

• action:https://github.com/cmbjxxiao/rt-thread/actions/runs/16560959690

]

当前拉取/合并请求的状态 Intent for your PR

必须选择一项 Choose one (Mandatory):

• 本拉取/合并请求是一个草稿版本 This PR is for a code-review and is intended to get feedback
• 本拉取/合并请求是一个成熟版本 This PR is mature, and ready to be integrated into the repo

代码质量 Code Quality：

我在这个拉取/合并请求中已经考虑了 As part of this pull request, I've considered the following:

• 已经仔细查看过代码改动的对比 Already check the difference between PR and old code
• 代码风格正确，包括缩进空格，命名及其他风格 Style guide is adhered to, including spacing, naming and other styles
• 没有垃圾代码，代码尽量精简，不包含#if 0代码，不包含已经被注释了的代码 All redundant code is removed and cleaned up
• 所有变更均有原因及合理的，并且不会影响到其他软件组件代码或BSP All modifications are justified and not affect other components or BSP
• 对难懂代码均提供对应的注释 I've commented appropriately where code is tricky
• 代码是高质量的 Code in this PR is of high quality
• 已经使用formatting 等源码格式化工具确保格式符合RT-Thread代码规范 This PR complies with RT-Thread code specification
• 如果是新增bsp, 已经添加ci检查到.github/workflows/bsp_buildings.yml 详细请参考链接BSP自查

[github-actions]

📌 Code Review Assignment

🏷️ Tag: components

Reviewers: @Maihuanyi

Changed Files (Click to expand)

• components/drivers/block/partitions/efi.h
• components/drivers/include/drivers/nvme.h

---

📊 Current Review Status (Last Updated: 2025-08-06 10:27 CST)

• ⌛ @Maihuanyi Pending Review

---

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[illustriousness]

The __packed qualifier sets the alignment of any valid type to 1.
看起来不太对啊 这个宏我猜想本意是想支持任意字节紧凑对齐的(虽然大家常用的基本只是1字节)
据我了解 ac5任意字节对齐的方式可以是下面这样

#pragma pack(2)  // 强制后续所有结构体按 2 字节对齐

typedef struct {
    uint8_t  a;    // 偏移 0
    uint16_t b;    // 偏移 2 (自动跳过 1 字节)
    uint32_t c;    // 偏移 4
} MyStruct;        // 总大小 = 8 字节

#pragma pack()     // 恢复默认对齐

[illustriousness]

The __packed qualifier sets the alignment of any valid type to 1. 看起来不太对啊 这个宏我猜想本意是想支持任意字节紧凑对齐的(虽然大家常用的基本只是1字节) 据我了解 ac5任意字节对齐的方式可以是下面这样

#pragma pack(2)  // 强制后续所有结构体按 2 字节对齐

typedef struct {
    uint8_t  a;    // 偏移 0
    uint16_t b;    // 偏移 2 (自动跳过 1 字节)
    uint32_t c;    // 偏移 4
} MyStruct;        // 总大小 = 8 字节

#pragma pack()     // 恢复默认对齐

抱歉 我的理解可能有误 似乎这个宏只是为了1字节对齐 如果是这样的话 当前这个是可以的

#define rt_packed(declare)          __packed declare

不过建议一个PR只改一个 我看你还修改了其他文件

[Copilot]

Pull Request Overview

This PR fixes memory alignment issues in ARM Compiler v4/v5 by properly defining the rt_packed macro to use __packed instead of an empty definition. The change addresses memory corruption problems that occur when using MDK5 compiler due to improper byte alignment in data structures.

• Updates rt_packed macro definition for ARM Compiler versions below 6.01.05 to use __packed
• Fixes existing struct definitions to use the corrected packed attribute syntax
• Resolves memory corruption issue in the find_valid_gpt function caused by incorrect sizeof calculations

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
include/rtcompiler.h	Updates rt_packed macro to use __packed for ARM Compiler v4/v5
components/drivers/include/drivers/nvme.h	Converts struct definition to use rt_packed macro correctly
components/drivers/block/partitions/efi.h	Adds packed attribute to guid_t typedef struct

Comments suppressed due to low confidence (1)

components/drivers/block/partitions/efi.h:33

• The syntax 'typedef struct rt_packed' is incorrect. Based on the rt_packed macro definition change, this should be 'rt_packed(typedef struct' with a corresponding closing parenthesis, or use 'typedef rt_packed(struct' to match the pattern used in nvme.h.

typedef struct rt_packed

[Maihuanyi]

LGTM