deeply love linux

install java on linux

2009-09-10T00:08:00.001-07:00

chmod +x jdk-6u16-linux-x64-rpm.bin

su -c ./jdk-6u16-linux-x64-rpm.bin

software raid in linux

2009-01-13T22:11:00.001-08:00

create raid:

mdadm --create --verbose /dev/md0 --level=0 --raid-device=2 /dev/sda1 /dev/sdb1

stop raid:

mdadm --manage --stop /dev/md0

inode

2009-01-12T19:35:00.000-08:00

An inode is a data structure on a traditional Unix-style file system such as UFS or ext3. An inode stores basic information about a regular file, directory, or other file system object.

see inode number of a file:

ex: ls -i test3.c

715775 test3.c

see info about the file

ex: stat test3.c

File: `test3.c'

Size: 451 Blocks: 8 IO Block: 4096 regular file

Device: 303h/771d Inode: 715775 Links: 1

Access: (0644/-rw-r--r--) Uid: ( 0/ root) Gid: ( 0/ root)

Access: 2009-01-06 22:11:55.000000000 +0800

Modify: 2008-12-22 17:43:56.000000000 +0800

Change: 2008-12-22 17:43:56.000000000 +0800

e2fsck

2009-01-12T19:33:00.001-08:00

check file system

ex:

e2fsck -f /dev/sda2

dumpe2fs

2009-01-12T19:25:00.000-08:00

dump ext2/ext3 filesystem information

ex:

dumpe2fs /dev/hda1

mpe2fs 1.38 (30-Jun-2005)

Filesystem volume name: /

Last mounted on:

Filesystem UUID: 1004b524-1c21-4829-bb94-0b5dada664c8

Filesystem magic number: 0xEF53

Filesystem revision #: 1 (dynamic)

Filesystem features: has_journal ext_attr resize_inode dir_index filetype sparse_super large_file

Default mount options: user_xattr acl

Filesystem state: clean

Errors behavior: Continue

Filesystem OS type: Linux

Inode count: 2560864

Block count: 2560351

Reserved block count: 128017

Free blocks: 1215812

Free inodes: 2431393

First block: 0

Block size: 4096

Fragment size: 4096

Reserved GDT blocks: 625

Blocks per group: 32768

Fragments per group: 32768

Inodes per group: 32416

Inode blocks per group: 1013

Filesystem created: Tue Aug 5 18:03:45 2008

Last mount time: Thu Jan 1 05:36:59 2009

Last write time: Thu Jan 1 09:26:35 2009

Mount count: 95

Maximum mount count: -1

Last checked: Tue Aug 5 18:03:45 2008

Check interval: 0 ()

Reserved blocks uid: 0 (user root)

Reserved blocks gid: 0 (group root)

First inode: 11

Inode size: 128

Journal inode: 8

Default directory hash: tea

Directory Hash Seed: 2b724a84-72d7-4a1e-a4fb-e9d5d09e4581

Journal backup: inode blocks

Group 0: (Blocks 0-32767)

Primary superblock at 0, Group descriptors at 1-1

Reserved GDT blocks at 2-626

Block bitmap at 627 (+627), Inode bitmap at 628 (+628)

Inode table at 629-1641 (+629)

0 free blocks, 32405 free inodes, 2 directories

Free blocks:

Free inodes: 12-32416

Group 1: (Blocks 32768-65535)

Backup superblock at 32768, Group descriptors at 32769-32769

Reserved GDT blocks at 32770-33394

Block bitmap at 33395 (+627), Inode bitmap at 33396 (+628)

Inode table at 33397-34409 (+629)

29415 free blocks, 32416 free inodes, 0 directories

Free blocks: 36121-65535

Free inodes: 32417-64832

Group 2: (Blocks 65536-98303)

Block bitmap at 65536 (+0), Inode bitmap at 65537 (+1)

Inode table at 65538-66550 (+2)

31746 free blocks, 32414 free inodes, 1 directories

Free blocks: 66552-88063, 88069-96255, 96257-98303

Free inodes: 64834, 64836-97248

Group 3: (Blocks 98304-131071)

Backup superblock at 98304, Group descriptors at 98305-98305

Reserved GDT blocks at 98306-98930

Block bitmap at 98931 (+627), Inode bitmap at 98932 (+628)

Inode table at 98933-99945 (+629)

30813 free blocks, 32396 free inodes, 0 directories

Free blocks: 99946-114687, 114689-122879, 123192-131071

Free inodes: 97268, 97270-129664

Group 4: (Blocks 131072-163839)

Block bitmap at 131072 (+0), Inode bitmap at 131073 (+1)

Inode table at 131074-132086 (+2)

31734 free blocks, 32416 free inodes, 0 directories

Free blocks: 132088-151440, 151459-163839

Free inodes: 129665-162080

Group 5: (Blocks 163840-196607)

Backup superblock at 163840, Group descriptors at 163841-163841

Reserved GDT blocks at 163842-164466

Block bitmap at 164467 (+627), Inode bitmap at 164468 (+628)

Inode table at 164469-165481 (+629)

13148 free blocks, 30388 free inodes, 212 directories

Free blocks: 165518-165522, 165524-165531, 165533-165535, 165537-165538, 165541-165546, 165548-165554, 165558-165562, 165573, 165576-165818, 165820-165887, 165891-167936, 167938, 167940-168618, 168807-168922, 169101-169226, 169381-169403, 169638-169760, 170300, 170390-170416, 170611-170692, 170695-170790, 170993-171100, 171288-171541, 171640-171760, 172077-172296, 172387-172655, 172733-174079, 174081-174083, 174085-176127, 176129, 176133-176135, 176150-176580, 176718-176829, 177002-177018, 177053-177117, 177286-177411, 177677-177699, 177748-177781, 177847-177969, 178312, 178467-178591, 178786-178863, 178996-179026, 179633-179735, 179834-179880, 179910-180006, 180224, 180531-180579, 180670-180752, 180773-180969, 180976-180997, 181028-181096, 181172-181280, 181518-181865, 182000-182061, 182216-182271, 182283, 184320, 184322, 186381, 189062, 189065, 189071-189098, 189311-189648, 189799-190039, 190297-190463, 190471, 190476-190639, 190705-190751, 190849-190909, 190920-191024, 191035-191661, 191672-191953, 191974-192124, 192183-192457, 193135, 193138-193154, 193533-193604, 193714-193800, 194381-194390, 194408-194427, 196328, 196459

Free inodes: 164072, 164077, 164111-194496

strace

2008-12-22T18:35:00.001-08:00

trace system call and signals

linux multipath

2008-12-22T18:20:00.000-08:00

load driver:

1. chkconfig boot.multipath on

2.chkconfig multipathd on

3. /etc/init.d/boot.multipath start

4. /etc/init.d/multipathd start

query multipath status:

multipath -l

stop multipath service:

1. /etc/init.d/boot.multipath stop

2. /etc/init.d/multipathd stop

/etc/scsi_id.config:

the info related to multipath

how to decide multipath:

the sds with the same uuid are combined into a dm

scsi_id -g -s /block/sda can get uuid

for red hat:

default multipath is not triggered

modify /etc/multipath.conf :

comment blacklist

remove dm:

multipath -F

multipath stop

iometer

2008-12-17T17:53:00.000-08:00

In windows : GUI

In linux: agent

Use windows iometer GUI to connect to linux iometer agent to get io information

run iometer agent in linux:

./dynamo -i windows_gui_ip -m linux_agent_ip

change log level & enable sysrq

2008-12-15T03:51:00.000-08:00

echo 9 > /proc/sysrq-trigger

echo 1 > /proc/sys/kernel/sysrq

alt + sysrq + p : show cpu info

alt + sysrq + t : show current task list

alt + sysrq + m : show memory info

redirect output from serial port

2008-12-15T03:46:00.000-08:00

1. modify bios:

(1)Change BIOS settings /Server/Serial Console Features/BIOS Redirection Port to

[Serial port 1 or 2]

(2)change direct to modem

2. modify /boot/grub/menu.lst for suse

modify /boot/grub/grub.conf for red hat

console=ttyS0, 115200,vt100

3. modify /ect/inittab

c0:2345:respawn:/sbin/agetty ttyS0 19200 vt100

4. modify /etc/securetty

ttyS0

How to Scan new LUNs on Linux with QLogic driver

2008-12-10T18:16:00.001-08:00

http://bash.cyberciti.biz/diskadmin/rescan-linux-scsi-bus/

line number

2008-12-10T00:59:00.000-08:00

nl: number lines

cpu info

2008-12-09T03:56:00.001-08:00

cat /proc/cpuinfo

interrupt context

2008-12-09T02:19:00.000-08:00

1. can not relinquish cpu by calling sleep functions

GFP_KERNEL

2008-12-09T02:13:00.000-08:00

allocate memory:

1. GFP_KERNEL:

kmalloc() is allowed to go to sleep and wait for pages to get freed up.

2.GFP_ATOMIC:

Used by interrupt context code to get hold of memory. In this mode, kmalloc() is not allowed to sleep-wait for free pages, so the probability of successful allocation with GFP_ATOMIC is lower than with GFP_KERNEL.

df

2008-11-16T22:46:00.001-08:00

show disk space

ex: df -h:

Filesystem Size Used Avail Use% Mounted on

/dev/hda3 9.9G 7.0G 2.4G 75% /

udev 8.0G 132K 8.0G 1% /dev

objdump

2008-11-16T22:37:00.000-08:00

show assembly of program:
ex:

objdump -D test.o

fsck

2008-11-13T19:38:00.000-08:00

check file system

tethereal

2008-10-30T00:38:00.000-07:00

ex:

tethereal -i eth7 host 192.168.5.41 -V > out

AF_UNSPEC

2008-10-21T01:17:00.000-07:00

ai_family = AF_UNSPEC;
AF_UNSPEC: for IPv4 & IPv6

accept

2008-10-17T01:43:00.000-07:00

#include
#include
int accept(int s, struct sockaddr *addr, socklen_t *addrlen);

return:
If successful, accept() returns a non-negative integer, which is a descriptor of the accepted socket.

chkconfig

2008-10-16T03:17:00.001-07:00

insserv

2008-10-16T02:56:00.001-07:00

scsi_execute_req

2008-09-11T22:24:00.001-07:00

int scsi_execute_req(struct scsi_device *sdev, const unsigned char *cmd,

int data_direction, void *buffer, unsigned bufflen,

struct scsi_sense_hdr *sshdr, int timeout, int retries)

scsi command code

2008-09-11T19:40:00.000-07:00

include/scsi/scsi.h

READ_6 0x08

WRITE_6 0x0a

READ_10 0x28

WRITE_10 0x2a

READ_16 0x88

WRITE_16 0x8a

website about block driver

2008-09-11T06:05:00.000-07:00

http://www.geocities.com/ravikiran_uvs/articles/

proc

2008-09-11T06:03:00.000-07:00

read_proc

struct dentry *proc_lookup(struct inode * dir, struct dentry *dentry)

drivers/scsi/sd.c

2008-09-10T10:01:00.000-07:00

the problem related to struct scsi_cmnd

struct scsi_cmnd

2008-09-09T09:25:00.000-07:00

/* These elements define the operation we are about to perform */

#define MAX_COMMAND_SIZE 16

unsigned char cmnd[MAX_COMMAND_SIZE];

sd_mod

2008-09-08T02:55:00.000-07:00

remove sd_mod will delete /dev/sd*

struct scsi_sense_hdr

2008-09-04T02:14:00.000-07:00

scsi_en.h

struct scsi_sense_hdr { /* See SPC-3 section 4.5 */

u8 response_code; /* permit: 0x0, 0x70, 0x71, 0x72, 0x73 */

u8 sense_key;

u8 asc;

u8 ascq;

u8 byte4;

u8 byte5;

u8 byte6;

u8 additional_length; /* always 0 for fixed sense format */

};

random number in driver

2008-08-29T00:31:00.000-07:00

get_random_bytes():

ex:

unsigned char uuid[16];

get_random_bytes(uuid, sizeof (uuid));

type definition

2008-08-28T20:13:00.000-07:00

struct block_device:

linux/fs.h

dev_t:

linux/types.h

struct page:

linux/mm_types.h

struct gendisk:

linux/genhd.h

struct request_queue:

linux/blkdev.h

wait_queue_head_t:

linux/wait.h

spinlock_t:

linux/spinlock_types.h

struct semaphore:

linux/semaphore.h

dmesg

2008-08-21T01:56:00.000-07:00

/var/log/messages

dhclient

2008-08-19T22:54:00.001-07:00

get new ip

dm

2008-08-19T00:38:00.000-07:00

//The request function that just remaps the bio built up by dm_merge_bvec

static int dm_request(struct request_queue *q, struct bio *bio)

call __split_bio

// Split the bio into several clones.

static int __split_bio(struct mapped_device *md, struct bio *bio)

call __clone_and_map with parameter ci

( ci.sector_count= bio_sectors(bio) )

static int __clone_and_map(struct clone_info *ci)

call split_bvec

sector_t

2008-08-18T20:17:00.001-07:00

typedef unsigned long sector_t;

mkfs

2008-08-17T23:17:00.001-07:00

create filesystem

ex:

mkfs -v /dev/hda3

struct bio

2008-08-17T19:28:00.000-07:00

struct bio:

struct block_device *bi_bdev;

struct bio_vec *bi_io_vec; /* the actual vec list */

unsigned short bi_vcnt; /* how many bio_vec's */

unsigned int bi_size; /* residual I/O count */

struct bio_vec:

  struct page     *bv_page;

  unsigned int    bv_len;

  unsigned int    bv_offset;

do I/O without request queue

2008-08-17T18:50:00.000-07:00

three steps:

1. define a make_request function

ex:

static int sbull_make_request(request_queue_t *q, struct bio *bio)

in the make_request function, transfer bio & call bio_endio(struct bio *bio, unsigned int bytes, int error) to signal completion

2. use blk_alloc_queue(GFP_KERNEL) to allocate a queue

3. call blk_queue_make_request(request_queue_t *queue, make_request_fn *func)

when make_request function return non-zero:

the bio is submitted again. Hence, we can modify bi_bdev & starting sector to redirect bio to another device

split bio into multiple chunks:

bio_split

kthread

2008-08-17T10:07:00.000-07:00

show kthread list

ps -ef

interrupt

2008-08-16T09:56:00.000-07:00

prevent interrupt entering critical section

method 1:

local_irq_disable(); /* Disable Interrupts in local CPU */

/* ... Critical Section ... */

local_irq_enable(); /* Enable Interrupts in local CPU */

method 2:

unsigned long flags;

Point A:

local_irq_save(flags); /* Disable Interrupts */

/* ... Critical Section ... */

local_irq_restore(flags); /* Restore state to what it was at point A */

spinlock & mutex

2008-08-16T09:45:00.000-07:00

spinlock ensures only one thread can enter critical section

spinlock example:

#include

spinlock_t mylock = SPIN_LOCK_UNLOCKED; /* Initialize */

/* Acquire the spinlock. This is inexpensive if there

* is no one inside the critical section. In the face of

* contention, spinlock() has to busy-wait.

spin_lock(&mylock);

/* ... Critical Section code ... */

spin_unlock(&mylock); /* Release the lock */

spinlock will busy-wait, mutex will sleep

mutex example:

#include

/* Statically declare a mutex. To dynamically

create a mutex, use mutex_init() */

static DEFINE_MUTEX(mymutex);

/* Acquire the mutex. This is inexpensive if there

* is no one inside the critical section. In the face of

* contention, mutex_lock() puts the calling thread to sleep.

mutex_lock(&mymutex);

/* ... Critical Section code ... */

mutex_unlock(&mymutex); /* Release the mutex */

linux開機設定

2008-08-16T01:24:00.000-07:00

GRUB:

/boot/grub/grub.conf or /boot/grub/menu.lst

grub.conf example:

default 0 #Boot the 2.6.23 kernel by default

timeout 5 #5 second to alter boot order or parameters

title kernel 2.6.23 #Boot Option 1

#The boot image resides in the first partition of the first disk

#under the /boot/ directory and is named vmlinuz-2.6.23. 'ro'

#indicates that the root partition should be mounted read-only.

kernel (hd0,0)/boot/vmlinuz-2.6.23 ro root=/dev/hda1

#Look under section "Freeing initrd memory:387k freed"

initrd (hd0,0)/boot/initrd

#...

LILO:

/etc/lilo.conf

compile driver

2008-08-16T01:10:00.000-07:00

method 1:

Makefile:

obj-m+=test.ko

make -C /usr/src/kernels/x.y.z/ M=`pwd` modules

kernel source module

2008-08-16T00:59:00.000-07:00

compile module:

1. cd /usr/src/linux-x.y.z/

2. make modules

install module

1. make modules_install

the generated module( ko) is stored in /lib/modules/x.y.z/kernel/

patch

2008-08-15T09:53:00.000-07:00

A patch is a text file containing source code differences between a development tree and the original snapshot from which the developer started work

apply patch:

ex: if x.y.z-mm2.bz2 is a patch, go to the directory of linux source

bzip2 -dc ../x.y.z-mm2.bz2 | patch -p1

create patch:

ex:

diff -Nur /path/originalKernal/ /path/newKernel > change changes.patch

global code browser

2008-08-15T02:14:00.000-07:00

install:

http://www.gnu.org/software/global/global.html

run:

1. go to directory of source code

2. gtags

3. htags ./codeTrace/

the generated html is in ./codeTrace/

find command

2008-08-13T20:16:00.000-07:00

find . -name "test.txt"

find text.txt under current directory

linux module location

2008-08-13T20:15:00.000-07:00

/lib/modules/2.6.18-92.el5/kernel/drivers

HZ & jiffies

2008-08-12T02:24:00.000-07:00

HZ是用來定義每一秒有幾次timer interrupts(time tick)

jiffies:

the number of time ticks since kernel start

ex:

unsigned long timeout=jiffies+ 3*HZ;

// the time after 3 second

time_after(jiffies, timeout)

convert from jiffies to seconds

divide by HZ

time related methods:

time_after: parameter is time tick

time_before: parameter is time tick

schedule_timeout: parameter is time tick

only schedule_timeout will give up processor

wait_event_timeout:

msleep: parameter is milliseconds

timer example( do something in the future):

#include

struct timer_list my_timer;

init_timer(&my_timer); /* Also see setup_timer() */

my_timer.expire = jiffies + n*HZ; /* n is the timeout in number

of seconds */

my_timer.function = timer_func; /* Function to execute

after n seconds */

my_timer.data = func_parameter; /* Parameter to be passed

to timer_func */

add_timer(&my_timer); /* Start the timer */

smp

2008-08-10T23:20:00.000-07:00

smp(多cpu)

rpm

2008-08-08T01:37:00.000-07:00

remove rpm:

rpm -e test

query info about specific rpm

ex:

rpm -q test

rpm for red hat and cent os

2008-08-07T20:25:00.000-07:00

Because red hat & cent os are related , we can get rpm for ret hat from rpm for cent os

init network

2008-08-07T00:51:00.000-07:00

開機網路設定:

/etc/sysconfig/network/

ifcfg-lo

ifcfg-eth0

blk_queue_make_request

2008-08-06T00:15:00.000-07:00

void blk_queue_make_request (request_queue_t * q, make_request_fn * mfn);

define an alternate make_request function for a device

ARGUMENTS

q
the request queue for the device to be affected
mfn
the alternate make_request function

linux driver command

2008-07-28T23:59:00.001-07:00

lsmod

顯示目前已經載入的模組清單

insmod

load module into kernel

ex: insmod hello.ko

rmmod:

remove module

modprobe:

like insmod, but also install dependent modules

(the module dependency is stored in /lib/modules/x.y.z/modules.dep)

modprobe -r:

remove module

modinfo:

show module info

linux kernel version

2008-07-28T18:40:00.000-07:00

red hat enterprise linux 4 update 4

core_2.6.9-42.EL_i686 & core_2.6.9-42.ELsmp_i686, core_2.6.9-42.ELsmp_x86_64, core_2.6.9-42.EL_x86_64

red hat enterprise linux 5 update 1

core_2.6.18-53.el5_i686 & core_2.6.18-53.el5_x86_64

red hat enterprise linux 5 update 2

core_2.6.18-92.el5_i686 & core_2.6.18-92.el5_x86_64

suse linux enterprise server 9

core_2.6.5-7.244-smp_x86_64

suse linux enterprise server 10

core_2.6.16.21-0.8-smp_i686 & core_2.6.16.21-0.8-smp_x86_64

suse linux enterprise server 10 sp1

core_2.6.16.46-0.12-smp_x86_64

suse linux enterprise server 10 sp2

core_2.6.16.60-0.21-default_i686 ,core_2.6.16.60-0.21-default_x86_64

LVM

2008-07-25T01:51:00.000-07:00

(1) 實體磁碟 --> PV( physical volume)

1. change id to 8e

ex:

(a) fdisk /dev/hda

(b) p

show information of hda

modify partition 1 's id to 8e

(d) w

alter partition table

(e) partprobe

let kernel read newest partition table

2. create pv

(a)pvscan:

show information of pv

(b)pvcreate

x11

2008-06-04T01:59:00.000-07:00

設定開機進入X11

edit /etc/inittab

id:3:initdefault:

設定開機進入文字介面:

edit /etc/inittab

id:5:initdefault:

x11 problem:

method 1:

edit /etc/X11/xorg.conf

defaultdepth =8

iscsi-initiator-utils

2008-06-03T00:21:00.000-07:00

start:

/etc/init.d/iscsi start

discovery lun

iscsiadm -m discovery -t sendtargets -p 192.168.5.122

192.168.5.122 is lun's ip

/etc/init.d/iscsi restart

connect to the lun 192.168.5.122, there is a new disk , sdd( use fdisk -l to show)

Format & mount

fdisk /dev/sdd

mke2fs -j -m 0 -O dir_index /dev/sdd1

mkdir /mnt/iscsi

mount /dev/sdd1 /mnt/iscsi

yum

2008-06-02T23:37:00.000-07:00

設定search path

/etc/yum.conf:

[main]

cachedir=/var/cache/yum

debuglevel=2

logfile=/var/log/yum.log

pkgpolicy=newest

distroverpkg=redhat-release

tolerant=1

exactarch=1

bsoletes=1

# PUT YOUR REPOS HERE OR IN separate files named file.repo

# in /etc/yum.repos.d

#[base]

#name=Red Hat Linux $releasever - $basearch - Base

#baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/$releasever/$basearch/

#[updates]

#name=Red Hat Linux $releasever - Updates

#baseurl=http://mirror.dulug.duke.edu/pub/yum-repository/redhat/updates/$releasever/

[dag]

name=Dag RPM Repository for Red Hat Enterprise Linux

baseurl=http://apt.sw.be/redhat/el4/en/i386/dag/

gpgcheck=1

enabled=1

[freshrpms]

name=FreshRPMs

baseurl=http://dag.freshrpms.net/redhat/el4/en/i386/dag/

gpgcheck=1

enabled=1

[rpmfind]

name=RPMFind.net

baseurl=http://rpmfind.net/linux/dag/redhat/el4/en/i386/dag/

gpgcheck=1

enabled=1

[pdx.edu]

name=PDX.edu

baseurl=http://mirrors.cat.pdx.edu/dag/redhat/el4/en/i386/dag/

gpgcheck=1

enabled=1

Open-iSCSI

2008-06-02T20:45:00.000-07:00

install 2.0-869.2

make

start:

rcopen-iscsi start

discovery:

iscsiadm -m discovery -t st -p 192.168.4.123

update chap information:

iscsiadm -m node -p 192.168.4.123 --op=update \

--name=node.session.auth.authmethod --value=CHAP

iscsiadm -m node -p 192.168.4.123 --op=update \     --name=node.session.auth.username --value=andy

iscsiadm -m node -p 192.168.4.123 --op=update \     --name=node.session.auth.password --value=1234

login:

iscsiadm -m node -p 192.168.4.123 -l

or

iscsiadm -m node -r nodeId -l

the disk added after login is in /dev/sd*

delete record:

iscsiadm -m node -o delete

or

rm -rf /etc/iscsi/nodes/*

logout

iscsiadm -m node -U all

daemon:

/etc/init.d/iscsi

increase iscsi ping time to prevent a lot of io error messages

node.conn[0].timeo.noop_out_interval = X

ode.conn[0].timeo.noop_out_timeout = X

open_by_devnum

2008-05-07T19:31:00.000-07:00

struct block_device *open_by_devnum(dev_t dev, unsigned mode)

struct bio

2008-05-07T18:41:00.000-07:00

struct bio {

sector_t bi_sector; // beginning sector

struct bio *bi_next;

struct block_device *bi_bdev;

unsigned short bi_vcnt;

unsigned short bi_idx; // an offset into the bi_io_vec array

struct bio_vec *bi_io_vec;

...

};

generic_make_request

2008-05-07T01:58:00.000-07:00

void generic_make_request (struct bio * bio);

make I/O requests of block devices.

It is passed a &struct bio, which describes the I/O that needs to be done.

the success/failure status of the request, along with notification of completion,

is delivered asynchronously through the bio->bi_end_io function

The caller of generic_make_request must make sure that bi_io_vec are set to describe the memory buffer, and that bi_dev and bi_sector are set to describe the device address, and the bi_end_io and optionally bi_private are set to describe how completion notification should be signaled.

MKDEV

2008-05-06T20:40:00.000-07:00

dev_t a= MKDEV( int major, int minor )

get major & minor

MIJOR( a ) & MINOR( a)

struct gendisk

2008-05-06T20:09:00.000-07:00

int major

int first_minor

first minor number associated with disk

int minors

range of minor numbers associated with disk. It control disk's max partition number

char disk_name[32]

struct gendisk *alloc_disk(int minors)

2008-05-06T18:55:00.000-07:00

allocate gendisk

system_utsname

2008-05-06T04:33:00.001-07:00

add_disk

2008-05-06T04:20:00.000-07:00

void add_disk(struct gendisk *disk);

add the disk to the list of active disks

the disk is active now

ioctl communication between kernel and user space

2008-05-06T02:18:00.000-07:00

use block device as example:

user space program:

struct Test_info test_info;

ioctl ( fd, ADD, &test_info);

driver:

1. define a function to deal with ioctl operation & assign this function

to struct block_device_operations

ex:

define a function test_ioctl

struct block_device_operations test_ops;

test_ops.ioctl = test_ioctl

2. define the function to deal with ioctl operation

it will receive two important parameters.

One is command, the other is argument.

From out example, the command received is ADD, the parameter received is &test_info

3. copy data from user space to kernel space

use copy_from_user

copy_from_user

2008-05-06T02:04:00.000-07:00

copy_from_user(void *to, const void *from, long n);

to: point to kernel-space address

from : point to user-space address

function stat

2008-05-05T00:44:00.000-07:00

int stat(const char *restrict path, struct stat *restrict buf);

get file status

struct stat {

dev_t st_dev;

ino_t st_ino;

mode_t st_mode;

nlink_t st_nlink;

uid_t st_uid;

gid_t st_gid;

dev_t st_rdev;

off_t st_size;

time_t st_atime;

time_t st_mtime;

time_t st_ctime;

blksize_t st_blksize;

blkcnt_t st_blocks;

mode_t st_attr;

};

structure sg_io_hdr_t

2008-05-04T23:53:00.000-07:00

getopt

2008-05-04T20:06:00.000-07:00

getopt(int argc, char * const argv[], const char *optstring)

get option character from command line argument list

ex:getopt(argc, argv, “bf:")

options are b & f

strdup

2008-05-04T20:00:00.001-07:00

char * strdup(const char *s1);

allocates sufficient memory for a copy of the string s1,

does the copy, and returns a pointer to it.

strstr

2008-05-04T19:50:00.000-07:00

strstr(const char *s1, const char *s2);

locate a substring in a string

struct utsname & uname

2008-05-04T19:13:00.000-07:00

struct utsname

hold information returned by the uname function

uname(struct utsname *name)

store information identifying the current system in the structure pointed to by name.

vnc

2008-04-30T01:38:00.000-07:00

start:

vncserver