DMA related kernel APIs

dma_map_single
  ==> map DMA address for virtual memory,
  ==>use kmalloc if continuous memory is not enough, it returens fail
dma_unmap_single
  ==> free memory by allocating dma_map_single
dma_alloc_cohernet
  ==> allocate coherent memory for DMA
  ==> it allocates memory in conherent area,
  ==> refer to memory.h in architecture
  ==> it can be decided by CONSISTENT_DMA_SIZE

other APIs
  ==> dma_pool_create
  ==> dma_pool_alloc
  ==> dma_pool_free
  ==> dma_pool_destory
  ==> dma_alloc_writecombine

Also you can decide dma memory attributes by using kernel APIs

For more detail,  refer to dma-api.txt in kernel doc

condiserations when you alloc DMA memory

1. allocate meory in coherent area ?
2. use memory as like pool?
3. how mush you are using coherent memory
4. swap area is used or not

But everytime you can not have enough memory......if you have, it's not real

inetutil cross compile - ( telnetd )

inetutil includes various network utils
such as telnet client, telnet daemon, tftp, and so on

download  source code

http://ftp.gnu.org/gnu/inetutils/

untar inetutils-1.8.tar.gz

and configure

# ./configure --host=arm-none-linux-gnueabi --build=i686 --prefix=/usr/bin
# make

I have compile error while building ifconfig,
just disable ifconfig then succeeded

# ./configure --host=arm-none-linux-gnueabi --build=i686 --prefix=/usr/bin --disable-ifconfig
# make

if you want to find other tool that is not included in inetutils
try to find net-tools

http://sourceforge.net/projects/net-tools/

pciutils build and install

Introduction

The PCI Utilities package contains a library for portable access to PCI bus configuration registers and several utilities based on this library.

- lspci: displays detailed information about all PCI buses and devices.
- setpci: allows to read from and write to PCI device configuration
    registers. For example, you can adjust the latency timers with it.
    CAUTION: There is a couple of dangerous points and caveats, please read
    the manual page first!
- update-pciids: download the current version of the pci.ids file.

For more detail , refer to README file in this package

download

ftp://atrey.karlin.mff.cuni.cz/pub/linux/pci/
https://ftp.kernel.org/pub/software/utils/pciutils/
or git tree
git://git.kernel.org/pub/scm/utils/pciutils/pciutils.git

Configure and build for cross compile

pci-util does not support configure.

$ make CROSS_COMPILE=arm-none-linux-gnueabi- HOST=arm-none-linux PREFIX=/targetnfs/durota/rfs/user/local/pciutils all
$make install

strip option is defined as below inside of make file

STRIP=-s

and install includes below

$(INSTALL) -c -m 755 $(STRIP) lspci setpci $(DESTDIR)$(SBINDIR)

change makefile as below

STRIP=$(CROSS_COMPILE)strip
$(STRIP) lspci
$(STRIP) setpci
$(INSTALL) -c -m 755 lspci setpci $(DESTDIR)$(SBINDIR)

or just remove $(STRIP)

$(INSTALL) -c -m 755  lspci setpci $(DESTDIR)$(SBINDIR)

simple busybox build

just do it

 make ARCH=arm CROSS_COMPILE=arm-none-linux-gnueabi- CONFIG_PREFIX=../rootfs_skel_tmp/ install

getting kernel cmdline in kernel

using the macro as below

__setup("console=", console_setup);

it means

if meet "console=" in cmd line call  console_setup

Unhandled fault: external abort on non-linefetch

I found this error message when access memory io

"Unhandled fault: external abort on non-linefetch"

if the device is not powered properly this message shows
It means Memory io address is assigned by kernel but io does not work.
check the device power stastus.

I power up the device in u-boot , then I could aceesse it

Embeded QT installation

Officail Home
http://qt.nokia.com/

Download

http://get.qt.nokia.com/qt/source/
http://qt.nokia.com/downloads/embedded-linux-cpp

References
http://processors.wiki.ti.com/index.php/Building_Qt#Building_Qt.C2.A0