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原创 ARMv8 ELx VBAR

VBAR_EL1, Vector Base Address Register (EL1)Holds the vector base address for any exception that is taken to EL1.VBAR_EL2, Vector Base Address Register (EL2)Holds the vector base address f...

原创 EXT4 MAP

const struct file_operations ext4_file_operations = { .llseek = ext4_llseek, .read_iter = ext4_file_read_iter, .write_iter = ext4_file_write_iter, .unlocked_ioctl = ext4_...

原创 Linux softirq

static struct softirq_action softirq_vec[NR_SOFTIRQS];DEFINE_PER_CPU(struct task_struct *, ksoftirqd);const char * const softirq_to_name[NR_SOFTIRQS] = { "HI", "TIMER", "NET_TX",...

原创 QCOM KERNEL log for DTB

[ 0.000000] Initializing cgroup subsys cpu[ 0.000000] Initializing cgroup subsys cpuacct[ 0.000000][ 0.000000] Boot CPU: AArch64 Processor [410fd034][ 0.000000] Machine: Qualcomm T...

原创 ARM64 DTS 处理-早期处理

setup_arch() // arch/arm64/kernel/setup.c --> setup_machine_fdt(__fdt_pointer); 检查DTB是否正确，以及早期配置系统 --> unflatten_device_tree();对DTB进行解析，填充设备树结构下内核针对设备树定义的struct device_node类型对象初始化。st...

原创 Linux ramfs, rootfs and initramfs

ramfs, rootfs and initramfs October 17, 2005 Rob Landley <[email protected]> =============================What is ramfs?--------------Ramfs is a very simple filesystem that exports Linux's disk...

原创 ext4 inode 分配

原创 驱动调用栈

[ 14.873268] [<ffffff800808c078>] dump_backtrace+0x0/0x4b0[ 14.881364] [<ffffff800808c53c>] show_stack+0x14/0x1c[ 14.888952] [<ffffff80087579d8>] dump_stack+0x78/0x98[ 14....

原创 ARM GICv3 研究学习 中断状态

对于GICv3来说，每个中断都关联了一个状态机，其用于描述每个中断的状态。GICv3 提供的每个中断的中断状态机Inactive:描述中断没有到来的状态，这里的定义是，不是处于active和pending状态。Pending:中断信号已经被asserted，即中断已经到来，并且被硬件识别到，这里是指GICv3的硬件识别到，这个可以是硬件产生或者软件产生的。此时处于等待目标cor...

原创 kernel_log之 version

Linux kernel log 版本与编译信息一般利用版本和编译信息用于确定每次修改内核代码后，了解本次运行是否是编译的kernel 镜像。上面这个打印位于start_kernel 函数的下面代码中：asmlinkage __visible void __init start_kernel(void){ char *command_line; char *afte...

原创 irq_enter

/** Enter an interrupt context.*/void irq_enter(void){ rcu_irq_enter(); if (is_idle_task(current) && !in_interrupt()) { /* * Prevent raise_softirq from needlessl...

转载 Watchdog

A watchdog is a fixed-length counter that enables a system to recover from an unexpected hardware or software catastrophe. Unless the system periodically resets the watchdog timer, the watchdog timer ...

原创 Linux 子进程pgd处理

进程创建 fork函数运行。copy_mm()--> dup_mmstatic struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p, struct user_namespace *user_ns){ mm->mmap = NULL; mm->mm_rb = RB_ROOT;

原创 Linux 内核页表初始化

前面我们讨论了页描述符对象分配，以及初始化。接下来我们再来了解内核页表建立初始化处理。针对ARM64进行。start_kernel --> setup_arch --> paging_init()void __init paging_init(void){ phys_addr_t pgd_phys = early_pgtable_alloc(); 分配页全局目录表地址

原创 Linux初始化页描述符对象

在前面我们讨论了内存节点node_mem_map成员的初始化。了解到此成员其实是以struct page为单位的数组，数组大小跟此节点内存大小相关，那么这些描述符是何时初始化呢，当前主要是在mem_init函数进行设置。start_kernel() --> mm_init --> mem_init()需要注意的是mem_init是跟体系结构相关的函数，比如针对ARM64的实现函数：

原创 Linux内存管理之mem_map对象

在linux内核中，所有的物理内存都用struct page结构来描述，这些对象以数组形式存放，而这个数组的地址就是mem_map。内核以节点node为单位，每个node下的物理内存统一管理，也就是说在表示内存node的描述类型struct pglist_data中，有node_mem_map这个成员，其针对平坦型内存进行描述(CONFIG_FLAT_NODE_MEM_MAP)，与此相反的是S

原创 Linux printk

printk("A0:%lld\n",  ktime_to_ns(ktime_get())); printk("A1:%lld\n",  ktime_to_ns(ktime_get()));[   40.059130] A0:40056438422[   40.061813] A1:40059121391[   40.064527] A0:40061834828

原创 ext4 节点inode.i_block描述

The Contents of inode.i_block Depending on the type of file an inode describes, the 60 bytes of storage in inode.i_block can be used in different ways. In general, regular files and directories will

原创 ext4 节点表

Inode Table In a regular UNIX filesystem, the inode stores all the metadata pertaining to the file (time stamps, block maps, extended attributes, etc), not the directory entry. To find the informatio

原创 ext5 块和节点表

Block and inode Bitmaps The data block bitmap tracks the usage of data blocks within the block group. The inode bitmap records which entries in the inode table are in use. As with most bitmaps, one bi

原创 ext4 块组介绍

Block Group Descriptors Each block group on the filesystem has one of these descriptors associated with it. As noted in the Layout section above, the group descriptors (if present) are the second ite

原创 EXT4 超级块介绍

The Super Block The superblock records various information about the enclosing filesystem, such as block counts, inode counts, supported features, maintenance information, and more. If the sparse_supe

原创 ext4 Overview

Overview An ext4 file system is split into a series of block groups. To reduce performance difficulties due to fragmentation, the block allocator tries very hard to keep each file's blocks within t

原创 ext4 Terminology

Terminology ext4 divides a storage device into an array of logical blocks both to reduce bookkeeping overhead and to increase throughput by forcing larger transfer sizes. Generally, the block size

原创 ext4 创建文件系统

Creating ext4 filesystems Creating a new ext4 filesystem is very easy once you have upgraded to e2fsprogs 1.41 or later. Simply type: # mke2fs -t ext4 /dev/DEV or # mkfs.ext4 /dev/DEV Once the files

转载 ext4 General Information

General Information Ext4 was released as a functionally complete and stable filesystem in Linux 2.6.28, and it's getting included in all the modern distros (in some cases as the default fs), so if you

翻译 ext4 EXT4 features

EXT4 features Compatibility Any existing Ext3 filesystem can be mounted as Ext4 without requiring any on-disk format changes. However, it is possible to upgrade an Ext3 filesystem to take advantage

原创 ext4 log1

ext4_map_blocks(): inode 8, flag 0, max_blocks 1,logical block 0ext4_map_blocks(): inode 8, flag 0, max_blocks 1,logical block 0ext4_map_blocks(): inode 8, flag 0, max_blocks 1,logical block 1ex

原创 ext4 block map log

blocks 0/1 requested for inode 8  size=88584192blocks 1/1 requested for inode 8  size=88584192blocks 2/1 requested for inode 8  size=88584192blocks 3/1 requested for inode 8  size=88584192bloc

原创 Linux buffer_head

enum bh_state_bits {    BH_Uptodate,    /* Contains valid data */    BH_Dirty,        /* Is dirty */    BH_Lock,        /* Is locked */    BH_Req,            /* Has been submitted for I/O */

原创 ext4 extent 寻址方案

Extent Tree In ext4, the file to logical block map has been replaced with an extent tree. Under the old scheme, allocating a contiguous run of 1,000 blocks requires an indirect block to map all 1,000

原创 ext4 直接和间接块寻址

Direct/Indirect Block Addressing In ext2/3, file block numbers were mapped to logical block numbers by means of an (up to) three level 1-1 block map. To find the logical block that stores a particul

原创 ext4 fs format

$ sudo mke2fs -t ext4 /dev/sdcmke2fs 1.42.9 (4-Feb-2014)/dev/sdc is entire device, not just one partition!Proceed anyway? (y,n) yFilesystem label=OS type: LinuxBlock size=4096 (log=2)Fra

原创 ext4 block info

Disk /dev/sdc: 15.5 GB, 15472047104 bytes32 heads, 63 sectors/track, 14989 cylinders, total 30218842 sectorsUnits = sectors of 1 * 512 = 512 bytesSector size (logical/physical): 512 bytes / 512

原创 ext4 节点映射块

/* * The ext4_map_blocks() function tries to look up the requested blocks, * and returns if the blocks are already mapped. * * Otherwise it takes the write lock of the i_data_sem and allocate

原创 ext4 定位块所在的块组

/* * The free blocks are managed by bitmaps.  A file system contains several * blocks groups.  Each group contains 1 bitmap block for blocks, 1 bitmap * block for inodes, N blocks for the inode

原创 ext4 读取块组下的节点位图

/* * Read the inode allocation bitmap for a given block_group, reading * into the specified slot in the superblock's bitmap cache. * Return buffer_head of bitmap on success or NULL. */static stru

原创 ext4 分配节点 核心层操作

static struct inode *alloc_inode(struct super_block *sb){    struct inode *inode;    if (sb->s_op->alloc_inode)        inode = sb->s_op->alloc_inode(sb);    else        inode = kmem_cach

原创 ext4 分配节点ext4_alloc_inode

/* * Called inside transaction, so use GFP_NOFS */static struct inode *ext4_alloc_inode(struct super_block *sb){    struct ext4_inode_info *ei;    ei = kmem_cache_alloc(ext4_inode_cachep

原创 EXT4之mount可选项

static const match_table_t tokens = { {Opt_bsd_df, "bsddf"}, {Opt_minix_df, "minixdf"}, {Opt_grpid, "grpid"}, {Opt_grpid, "bsdgroups"}, {Opt_nogrpid, "nogrpid"}, {Opt_nogrpid, "sysvgroups"