一、如何高效阅读Linux源码：基于clangd

uboot/busybox等都可以用这种方式，理论上说所有基于Make和Cmake的源码工程都可以用这套方案

阅读Linux源码最大问题在于调用链太复杂，一个函数或变量引用太多，source insight和cscope等基于文本检索类似的工具，分析都不够精确，clangd是在编译过程分析调用关系，结果要准确地多，使用效果极佳。下面截取几个图展示下clangd的强大之处

Kconfig和Makefile中定义的配置项宏如果为0，Clangd检索完VScode会把没走到的分支自动注释掉，大大降低我们分析源码时走错分支的可能性

右键ShowCallHierarchy调用栈分析一步到位

精准强大的代码补全

在写驱动时，对内核方法和对象的提示非常全和准确

创建索引非常快，5.10.99的内核全量创建索引只需约2分钟，busybox和uboot的源码十几秒就好了

创建索引非常快，5.10.99的内核全量创建索引只需约2分钟，busybox和uboot的源码十几秒就好了

搭建教程参考

https://blog.csdn.net/thisway_diy/article/details/127426986

二、写驱动时如何自动格式化并(最好和Linux内核源码一个风格！！！）

1.VScode安装Clang-Format插件

左侧插件市场搜索直接安装即可

2.给系统安装clang-format

以Ubuntu为例，其他系统类似

sudo apt-get install clang-format

3.从Linux源码根目录把.clang-format文件拷贝到自己的项目目录

5.10.99亲测官方源码就有.clang-format文件，不过4.x版本没有，应该是5.x引进的，方便内核开发人员统一编码风格的

防止的Linux内核源码版本低，这里拷贝一份过来，大家可以在自己的工程目录手动创建.clang-format文件，并把下面的内容复制进去

# SPDX-License-Identifier: GPL-2.0
#
# clang-format configuration file. Intended for clang-format >= 4.
#
# For more information, see:
#
#   Documentation/process/clang-format.rst
#   https://clang.llvm.org/docs/ClangFormat.html
#   https://clang.llvm.org/docs/ClangFormatStyleOptions.html
#
---
AccessModifierOffset: -4
AlignAfterOpenBracket: Align
AlignConsecutiveAssignments: false
AlignConsecutiveDeclarations: false
#AlignEscapedNewlines: Left # Unknown to clang-format-4.0
AlignOperands: true
AlignTrailingComments: false
AllowAllParametersOfDeclarationOnNextLine: false
AllowShortBlocksOnASingleLine: false
AllowShortCaseLabelsOnASingleLine: false
AllowShortFunctionsOnASingleLine: None
AllowShortIfStatementsOnASingleLine: false
AllowShortLoopsOnASingleLine: false
AlwaysBreakAfterDefinitionReturnType: None
AlwaysBreakAfterReturnType: None
AlwaysBreakBeforeMultilineStrings: false
AlwaysBreakTemplateDeclarations: false
BinPackArguments: true
BinPackParameters: true
BraceWrapping:AfterClass: falseAfterControlStatement: falseAfterEnum: falseAfterFunction: trueAfterNamespace: trueAfterObjCDeclaration: falseAfterStruct: falseAfterUnion: false#AfterExternBlock: false # Unknown to clang-format-5.0BeforeCatch: falseBeforeElse: falseIndentBraces: false#SplitEmptyFunction: true # Unknown to clang-format-4.0#SplitEmptyRecord: true # Unknown to clang-format-4.0#SplitEmptyNamespace: true # Unknown to clang-format-4.0
BreakBeforeBinaryOperators: None
BreakBeforeBraces: Custom
#BreakBeforeInheritanceComma: false # Unknown to clang-format-4.0
BreakBeforeTernaryOperators: false
BreakConstructorInitializersBeforeComma: false
#BreakConstructorInitializers: BeforeComma # Unknown to clang-format-4.0
BreakAfterJavaFieldAnnotations: false
BreakStringLiterals: false
ColumnLimit: 80
CommentPragmas: '^ IWYU pragma:'
#CompactNamespaces: false # Unknown to clang-format-4.0
ConstructorInitializerAllOnOneLineOrOnePerLine: false
ConstructorInitializerIndentWidth: 8
ContinuationIndentWidth: 8
Cpp11BracedListStyle: false
DerivePointerAlignment: false
DisableFormat: false
ExperimentalAutoDetectBinPacking: false
#FixNamespaceComments: false # Unknown to clang-format-4.0# Taken from:
#   git grep -h '^#define [^[:space:]]*for_each[^[:space:]]*(' include/ \
#   | sed "s,^#define \([^[:space:]]*for_each[^[:space:]]*\)(.*$,  - '\1'," \
#   | sort | uniq
ForEachMacros:- 'apei_estatus_for_each_section'- 'ata_for_each_dev'- 'ata_for_each_link'- '__ata_qc_for_each'- 'ata_qc_for_each'- 'ata_qc_for_each_raw'- 'ata_qc_for_each_with_internal'- 'ax25_for_each'- 'ax25_uid_for_each'- '__bio_for_each_bvec'- 'bio_for_each_bvec'- 'bio_for_each_bvec_all'- 'bio_for_each_integrity_vec'- '__bio_for_each_segment'- 'bio_for_each_segment'- 'bio_for_each_segment_all'- 'bio_list_for_each'- 'bip_for_each_vec'- 'bitmap_for_each_clear_region'- 'bitmap_for_each_set_region'- 'blkg_for_each_descendant_post'- 'blkg_for_each_descendant_pre'- 'blk_queue_for_each_rl'- 'bond_for_each_slave'- 'bond_for_each_slave_rcu'- 'bpf_for_each_spilled_reg'- 'btree_for_each_safe128'- 'btree_for_each_safe32'- 'btree_for_each_safe64'- 'btree_for_each_safel'- 'card_for_each_dev'- 'cgroup_taskset_for_each'- 'cgroup_taskset_for_each_leader'- 'cpufreq_for_each_entry'- 'cpufreq_for_each_entry_idx'- 'cpufreq_for_each_valid_entry'- 'cpufreq_for_each_valid_entry_idx'- 'css_for_each_child'- 'css_for_each_descendant_post'- 'css_for_each_descendant_pre'- 'device_for_each_child_node'- 'dma_fence_chain_for_each'- 'do_for_each_ftrace_op'- 'drm_atomic_crtc_for_each_plane'- 'drm_atomic_crtc_state_for_each_plane'- 'drm_atomic_crtc_state_for_each_plane_state'- 'drm_atomic_for_each_plane_damage'- 'drm_client_for_each_connector_iter'- 'drm_client_for_each_modeset'- 'drm_connector_for_each_possible_encoder'- 'drm_for_each_bridge_in_chain'- 'drm_for_each_connector_iter'- 'drm_for_each_crtc'- 'drm_for_each_encoder'- 'drm_for_each_encoder_mask'- 'drm_for_each_fb'- 'drm_for_each_legacy_plane'- 'drm_for_each_plane'- 'drm_for_each_plane_mask'- 'drm_for_each_privobj'- 'drm_mm_for_each_hole'- 'drm_mm_for_each_node'- 'drm_mm_for_each_node_in_range'- 'drm_mm_for_each_node_safe'- 'flow_action_for_each'- 'for_each_active_dev_scope'- 'for_each_active_drhd_unit'- 'for_each_active_iommu'- 'for_each_aggr_pgid'- 'for_each_available_child_of_node'- 'for_each_bio'- 'for_each_board_func_rsrc'- 'for_each_bvec'- 'for_each_card_auxs'- 'for_each_card_auxs_safe'- 'for_each_card_components'- 'for_each_card_dapms'- 'for_each_card_pre_auxs'- 'for_each_card_prelinks'- 'for_each_card_rtds'- 'for_each_card_rtds_safe'- 'for_each_card_widgets'- 'for_each_card_widgets_safe'- 'for_each_cgroup_storage_type'- 'for_each_child_of_node'- 'for_each_clear_bit'- 'for_each_clear_bit_from'- 'for_each_cmsghdr'- 'for_each_compatible_node'- 'for_each_component_dais'- 'for_each_component_dais_safe'- 'for_each_comp_order'- 'for_each_console'- 'for_each_cpu'- 'for_each_cpu_and'- 'for_each_cpu_not'- 'for_each_cpu_wrap'- 'for_each_dapm_widgets'- 'for_each_dev_addr'- 'for_each_dev_scope'- 'for_each_displayid_db'- 'for_each_dma_cap_mask'- 'for_each_dpcm_be'- 'for_each_dpcm_be_rollback'- 'for_each_dpcm_be_safe'- 'for_each_dpcm_fe'- 'for_each_drhd_unit'- 'for_each_dss_dev'- 'for_each_efi_memory_desc'- 'for_each_efi_memory_desc_in_map'- 'for_each_element'- 'for_each_element_extid'- 'for_each_element_id'- 'for_each_endpoint_of_node'- 'for_each_evictable_lru'- 'for_each_fib6_node_rt_rcu'- 'for_each_fib6_walker_rt'- 'for_each_free_mem_pfn_range_in_zone'- 'for_each_free_mem_pfn_range_in_zone_from'- 'for_each_free_mem_range'- 'for_each_free_mem_range_reverse'- 'for_each_func_rsrc'- 'for_each_hstate'- 'for_each_if'- 'for_each_iommu'- 'for_each_ip_tunnel_rcu'- 'for_each_irq_nr'- 'for_each_link_codecs'- 'for_each_link_cpus'- 'for_each_link_platforms'- 'for_each_lru'- 'for_each_matching_node'- 'for_each_matching_node_and_match'- 'for_each_member'- 'for_each_mem_region'- 'for_each_memblock_type'- 'for_each_memcg_cache_index'- 'for_each_mem_pfn_range'- '__for_each_mem_range'- 'for_each_mem_range'- '__for_each_mem_range_rev'- 'for_each_mem_range_rev'- 'for_each_migratetype_order'- 'for_each_msi_entry'- 'for_each_msi_entry_safe'- 'for_each_net'- 'for_each_net_continue_reverse'- 'for_each_netdev'- 'for_each_netdev_continue'- 'for_each_netdev_continue_rcu'- 'for_each_netdev_continue_reverse'- 'for_each_netdev_feature'- 'for_each_netdev_in_bond_rcu'- 'for_each_netdev_rcu'- 'for_each_netdev_reverse'- 'for_each_netdev_safe'- 'for_each_net_rcu'- 'for_each_new_connector_in_state'- 'for_each_new_crtc_in_state'- 'for_each_new_mst_mgr_in_state'- 'for_each_new_plane_in_state'- 'for_each_new_private_obj_in_state'- 'for_each_node'- 'for_each_node_by_name'- 'for_each_node_by_type'- 'for_each_node_mask'- 'for_each_node_state'- 'for_each_node_with_cpus'- 'for_each_node_with_property'- 'for_each_nonreserved_multicast_dest_pgid'- 'for_each_of_allnodes'- 'for_each_of_allnodes_from'- 'for_each_of_cpu_node'- 'for_each_of_pci_range'- 'for_each_old_connector_in_state'- 'for_each_old_crtc_in_state'- 'for_each_old_mst_mgr_in_state'- 'for_each_oldnew_connector_in_state'- 'for_each_oldnew_crtc_in_state'- 'for_each_oldnew_mst_mgr_in_state'- 'for_each_oldnew_plane_in_state'- 'for_each_oldnew_plane_in_state_reverse'- 'for_each_oldnew_private_obj_in_state'- 'for_each_old_plane_in_state'- 'for_each_old_private_obj_in_state'- 'for_each_online_cpu'- 'for_each_online_node'- 'for_each_online_pgdat'- 'for_each_pci_bridge'- 'for_each_pci_dev'- 'for_each_pci_msi_entry'- 'for_each_pcm_streams'- 'for_each_physmem_range'- 'for_each_populated_zone'- 'for_each_possible_cpu'- 'for_each_present_cpu'- 'for_each_prime_number'- 'for_each_prime_number_from'- 'for_each_process'- 'for_each_process_thread'- 'for_each_property_of_node'- 'for_each_registered_fb'- 'for_each_requested_gpio'- 'for_each_requested_gpio_in_range'- 'for_each_reserved_mem_range'- 'for_each_reserved_mem_region'- 'for_each_rtd_codec_dais'- 'for_each_rtd_codec_dais_rollback'- 'for_each_rtd_components'- 'for_each_rtd_cpu_dais'- 'for_each_rtd_cpu_dais_rollback'- 'for_each_rtd_dais'- 'for_each_set_bit'- 'for_each_set_bit_from'- 'for_each_set_clump8'- 'for_each_sg'- 'for_each_sg_dma_page'- 'for_each_sg_page'- 'for_each_sgtable_dma_page'- 'for_each_sgtable_dma_sg'- 'for_each_sgtable_page'- 'for_each_sgtable_sg'- 'for_each_sibling_event'- 'for_each_subelement'- 'for_each_subelement_extid'- 'for_each_subelement_id'- '__for_each_thread'- 'for_each_thread'- 'for_each_unicast_dest_pgid'- 'for_each_wakeup_source'- 'for_each_zone'- 'for_each_zone_zonelist'- 'for_each_zone_zonelist_nodemask'- 'fwnode_for_each_available_child_node'- 'fwnode_for_each_child_node'- 'fwnode_graph_for_each_endpoint'- 'gadget_for_each_ep'- 'genradix_for_each'- 'genradix_for_each_from'- 'hash_for_each'- 'hash_for_each_possible'- 'hash_for_each_possible_rcu'- 'hash_for_each_possible_rcu_notrace'- 'hash_for_each_possible_safe'- 'hash_for_each_rcu'- 'hash_for_each_safe'- 'hctx_for_each_ctx'- 'hlist_bl_for_each_entry'- 'hlist_bl_for_each_entry_rcu'- 'hlist_bl_for_each_entry_safe'- 'hlist_for_each'- 'hlist_for_each_entry'- 'hlist_for_each_entry_continue'- 'hlist_for_each_entry_continue_rcu'- 'hlist_for_each_entry_continue_rcu_bh'- 'hlist_for_each_entry_from'- 'hlist_for_each_entry_from_rcu'- 'hlist_for_each_entry_rcu'- 'hlist_for_each_entry_rcu_bh'- 'hlist_for_each_entry_rcu_notrace'- 'hlist_for_each_entry_safe'- '__hlist_for_each_rcu'- 'hlist_for_each_safe'- 'hlist_nulls_for_each_entry'- 'hlist_nulls_for_each_entry_from'- 'hlist_nulls_for_each_entry_rcu'- 'hlist_nulls_for_each_entry_safe'- 'i3c_bus_for_each_i2cdev'- 'i3c_bus_for_each_i3cdev'- 'ide_host_for_each_port'- 'ide_port_for_each_dev'- 'ide_port_for_each_present_dev'- 'idr_for_each_entry'- 'idr_for_each_entry_continue'- 'idr_for_each_entry_continue_ul'- 'idr_for_each_entry_ul'- 'in_dev_for_each_ifa_rcu'- 'in_dev_for_each_ifa_rtnl'- 'inet_bind_bucket_for_each'- 'inet_lhash2_for_each_icsk_rcu'- 'key_for_each'- 'key_for_each_safe'- 'klp_for_each_func'- 'klp_for_each_func_safe'- 'klp_for_each_func_static'- 'klp_for_each_object'- 'klp_for_each_object_safe'- 'klp_for_each_object_static'- 'kunit_suite_for_each_test_case'- 'kvm_for_each_memslot'- 'kvm_for_each_vcpu'- 'list_for_each'- 'list_for_each_codec'- 'list_for_each_codec_safe'- 'list_for_each_continue'- 'list_for_each_entry'- 'list_for_each_entry_continue'- 'list_for_each_entry_continue_rcu'- 'list_for_each_entry_continue_reverse'- 'list_for_each_entry_from'- 'list_for_each_entry_from_rcu'- 'list_for_each_entry_from_reverse'- 'list_for_each_entry_lockless'- 'list_for_each_entry_rcu'- 'list_for_each_entry_reverse'- 'list_for_each_entry_safe'- 'list_for_each_entry_safe_continue'- 'list_for_each_entry_safe_from'- 'list_for_each_entry_safe_reverse'- 'list_for_each_prev'- 'list_for_each_prev_safe'- 'list_for_each_safe'- 'llist_for_each'- 'llist_for_each_entry'- 'llist_for_each_entry_safe'- 'llist_for_each_safe'- 'mci_for_each_dimm'- 'media_device_for_each_entity'- 'media_device_for_each_intf'- 'media_device_for_each_link'- 'media_device_for_each_pad'- 'nanddev_io_for_each_page'- 'netdev_for_each_lower_dev'- 'netdev_for_each_lower_private'- 'netdev_for_each_lower_private_rcu'- 'netdev_for_each_mc_addr'- 'netdev_for_each_uc_addr'- 'netdev_for_each_upper_dev_rcu'- 'netdev_hw_addr_list_for_each'- 'nft_rule_for_each_expr'- 'nla_for_each_attr'- 'nla_for_each_nested'- 'nlmsg_for_each_attr'- 'nlmsg_for_each_msg'- 'nr_neigh_for_each'- 'nr_neigh_for_each_safe'- 'nr_node_for_each'- 'nr_node_for_each_safe'- 'of_for_each_phandle'- 'of_property_for_each_string'- 'of_property_for_each_u32'- 'pci_bus_for_each_resource'- 'pcm_for_each_format'- 'ping_portaddr_for_each_entry'- 'plist_for_each'- 'plist_for_each_continue'- 'plist_for_each_entry'- 'plist_for_each_entry_continue'- 'plist_for_each_entry_safe'- 'plist_for_each_safe'- 'pnp_for_each_card'- 'pnp_for_each_dev'- 'protocol_for_each_card'- 'protocol_for_each_dev'- 'queue_for_each_hw_ctx'- 'radix_tree_for_each_slot'- 'radix_tree_for_each_tagged'- 'rbtree_postorder_for_each_entry_safe'- 'rdma_for_each_block'- 'rdma_for_each_port'- 'rdma_umem_for_each_dma_block'- 'resource_list_for_each_entry'- 'resource_list_for_each_entry_safe'- 'rhl_for_each_entry_rcu'- 'rhl_for_each_rcu'- 'rht_for_each'- 'rht_for_each_entry'- 'rht_for_each_entry_from'- 'rht_for_each_entry_rcu'- 'rht_for_each_entry_rcu_from'- 'rht_for_each_entry_safe'- 'rht_for_each_from'- 'rht_for_each_rcu'- 'rht_for_each_rcu_from'- '__rq_for_each_bio'- 'rq_for_each_bvec'- 'rq_for_each_segment'- 'scsi_for_each_prot_sg'- 'scsi_for_each_sg'- 'sctp_for_each_hentry'- 'sctp_skb_for_each'- 'shdma_for_each_chan'- '__shost_for_each_device'- 'shost_for_each_device'- 'sk_for_each'- 'sk_for_each_bound'- 'sk_for_each_entry_offset_rcu'- 'sk_for_each_from'- 'sk_for_each_rcu'- 'sk_for_each_safe'- 'sk_nulls_for_each'- 'sk_nulls_for_each_from'- 'sk_nulls_for_each_rcu'- 'snd_array_for_each'- 'snd_pcm_group_for_each_entry'- 'snd_soc_dapm_widget_for_each_path'- 'snd_soc_dapm_widget_for_each_path_safe'- 'snd_soc_dapm_widget_for_each_sink_path'- 'snd_soc_dapm_widget_for_each_source_path'- 'tb_property_for_each'- 'tcf_exts_for_each_action'- 'udp_portaddr_for_each_entry'- 'udp_portaddr_for_each_entry_rcu'- 'usb_hub_for_each_child'- 'v4l2_device_for_each_subdev'- 'v4l2_m2m_for_each_dst_buf'- 'v4l2_m2m_for_each_dst_buf_safe'- 'v4l2_m2m_for_each_src_buf'- 'v4l2_m2m_for_each_src_buf_safe'- 'virtio_device_for_each_vq'- 'while_for_each_ftrace_op'- 'xa_for_each'- 'xa_for_each_marked'- 'xa_for_each_range'- 'xa_for_each_start'- 'xas_for_each'- 'xas_for_each_conflict'- 'xas_for_each_marked'- 'xbc_array_for_each_value'- 'xbc_for_each_key_value'- 'xbc_node_for_each_array_value'- 'xbc_node_for_each_child'- 'xbc_node_for_each_key_value'- 'zorro_for_each_dev'#IncludeBlocks: Preserve # Unknown to clang-format-5.0
IncludeCategories:- Regex: '.*'Priority: 1
IncludeIsMainRegex: '(Test)?$'
IndentCaseLabels: false
#IndentPPDirectives: None # Unknown to clang-format-5.0
IndentWidth: 8
IndentWrappedFunctionNames: false
JavaScriptQuotes: Leave
JavaScriptWrapImports: true
KeepEmptyLinesAtTheStartOfBlocks: false
MacroBlockBegin: ''
MacroBlockEnd: ''
MaxEmptyLinesToKeep: 1
NamespaceIndentation: None
#ObjCBinPackProtocolList: Auto # Unknown to clang-format-5.0
ObjCBlockIndentWidth: 8
ObjCSpaceAfterProperty: true
ObjCSpaceBeforeProtocolList: true# Taken from git's rules
#PenaltyBreakAssignment: 10 # Unknown to clang-format-4.0
PenaltyBreakBeforeFirstCallParameter: 30
PenaltyBreakComment: 10
PenaltyBreakFirstLessLess: 0
PenaltyBreakString: 10
PenaltyExcessCharacter: 100
PenaltyReturnTypeOnItsOwnLine: 60PointerAlignment: Right
ReflowComments: false
SortIncludes: false
#SortUsingDeclarations: false # Unknown to clang-format-4.0
SpaceAfterCStyleCast: false
SpaceAfterTemplateKeyword: true
SpaceBeforeAssignmentOperators: true
#SpaceBeforeCtorInitializerColon: true # Unknown to clang-format-5.0
#SpaceBeforeInheritanceColon: true # Unknown to clang-format-5.0
SpaceBeforeParens: ControlStatements
#SpaceBeforeRangeBasedForLoopColon: true # Unknown to clang-format-5.0
SpaceInEmptyParentheses: false
SpacesBeforeTrailingComments: 1
SpacesInAngles: false
SpacesInContainerLiterals: false
SpacesInCStyleCastParentheses: false
SpacesInParentheses: false
SpacesInSquareBrackets: false
Standard: Cpp03
TabWidth: 8
UseTab: Always
...

4.设置clang-format为默认格式化插件

操作如下

5.设置格式化时机为format on save

6.打开自己的代码文件，随便修改点，按Ctrl+S保存，代码即可自动格式化，而且和内核风格完全一样