Difference between revisions of "Xen ARM with Virtualization Extensions/Allwinner"

From Xen
(Update for latest upstream and sunxi trees)
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  +
== Hardware ==
this wiki talks about xen on [http://linux-sunxi.org/A20 A20](Cortex-A7 dual core, code name sun7i). [http://linux-sunxi.org/A31 A31](Cortex-A7 quad core, code name sun6i) should work as well.
 
   
  +
This wiki talks about Xen on Allwinner [http://linux-sunxi.org/A20 A20](Cortex-A7 dual core, code name sun7i).
== Compile u-boot ==
 
as described in [http://wiki.xen.org/wiki/Xen_ARM_with_Virtualization_Extensions#Firmware_Requirements Firmware_Requirements], xen need boot from non-secure hyper mode.
 
   
  +
The [http://linux-sunxi.org/A31 A31](Cortex-A7 quad core, code name sun6i) should work as well, but has not been as widely tested.
=== get the code ===
 
a worked branch is here:
 
https://github.com/bjzhang/u-boot-sunxi/tree/sunxi_hyp
 
   
  +
The following boards have been tested:
here is the details:
 
; merge the hypmode branch
 
git://git.linaro.org/people/aprzywara/u-boot.git hypmode_v4
 
branch into
 
git://github.com/linux-sunxi/u-boot-sunxi.git u-boot-sunxi
 
i tested hypmode_v4 with commit 3d2fc4e8 in u-boot-sunxi. hypmode_v5 should work as well.
 
; add [http://lists.xen.org/archives/html/xen-devel/2013-08/msg03040.html Ian Campbell patches] on it.
 
; enable arm generic timer for sunxi, xen dom0 kernel need this:
 
diff --git a/include/configs/sun7i.h b/include/configs/sun7i.h
 
index f0d9222..473d1eb 100644
 
--- a/include/configs/sun7i.h
 
+++ b/include/configs/sun7i.h
 
@@ -36,6 +36,8 @@
 
 
#define CONFIG_ARMV7_VIRT
 
 
+#define CONFIG_SYS_CLK_FREQ 24000000
 
+
 
#if defined(CONFIG_SYS_SECONDARY_ON)
 
#define CONFIG_BOARD_POSTCLK_INIT 1
 
#endif
 
   
  +
* A20
refernce: [http://lists.xen.org/archives/html/xen-devel/2013-08/msg03040.html bootwrapper can't be compiled for cubieboard2]
 
  +
** [http://linux-sunxi.org/Cubieboard2#Cubieboard2_.28A20.29 Cubieboard2] (note that the original Cubieboard does not support virtualisation)
  +
** [http://linux-sunxi.org/Cubietruck Cubietruck] (AKA Cubieboard 3)
  +
  +
== Bootloader ==
  +
  +
As described in [[Xen_ARM_with_Virtualization_Extensions#Firmware_Requirements|Firmware Requirements]], Xen need boot from non-secure hyper mode.
  +
  +
=== Source Code ===
  +
  +
sunxi support is not currently merged into mainline u-boot. Support for this platform is available in the [https://github.com/linux-sunxi/u-boot-sunxi/ u-boot-sunxi.git tree]
  +
  +
Hans de Goede maintains a branch which adds the necessary support for PSCI to enable SMP support and booting from non-secure hypervisor mode. See [https://github.com/jwrdegoede/u-boot-sunxi https://github.com/jwrdegoede/u-boot-sunxi], branch `sunxi-next`.
   
 
=== Compile ===
 
=== Compile ===
  +
for sd card
 
  +
See [http://linux-sunxi.org/U-boot] for more details on building U-boot for sunxi.
  +
  +
For [http://linux-sunxi.org/Bootable_SD_card sd card]:
 
make Cubieboard2 CROSS_COMPILE=arm-linux-gnueabihf- -j8
 
make Cubieboard2 CROSS_COMPILE=arm-linux-gnueabihf- -j8
  +
For [http://linux-sunxi.org/FEL/USBBoot USB/FEL boot]:
for usb boot
 
 
make Cubieboard2_FEL CROSS_COMPILE=arm-linux-gnueabihf- -j8
 
make Cubieboard2_FEL CROSS_COMPILE=arm-linux-gnueabihf- -j8
   
== Building Linux Dom0 ==
+
== Linux ==
  +
  +
=== Upstream Community ===
  +
  +
Support for the Allwinner processors in Linux is mainly a community effort, see [http://linux-sunxi.org/Main_Page the Linux Sunxi Wiki].
  +
  +
=== Source Code ===
  +
  +
Upstream Linux support for Allwinner processors is a work in progress. See [http://linux-sunxi.org/Linux_mainlining_effort Sunxi Linux mainlining effort] for current status.
  +
  +
As of 3.13-rc6 there is a lot of useful support in the mainline kernel, however the following are not present:
  +
* SATA AHCI support
  +
* MMC support
  +
* USB support
   
  +
Support for these can be found in the sunxi linux tree at [https://github.com/linux-sunxi/linux-sunxi https://github.com/linux-sunxi/linux-sunxi]. The `sunxi-next` contain stuff destined for the next Linux merge window, while `sunxi-devel` contains things targeting future versions. Both branches are rebasing.
First, we will build Linux for dom0 to have a device tree to provide to Xen.
 
   
  +
=== Building ===
You can get a tree from [https://github.com/bjzhang/linux-allwinner/tree/sun7i-xen-dom0 sun7i-xen-dom0] which is based on arokux sunxi usb branch.
 
the emac patch in this tree is needed for enable network in dom0.
 
i am confuse about what does "CONFIG XEN" mean. it will check the kernel features for dom0 and domU kernel.
 
if you want to a dom0 kernel, you need to uncheck all the FRONTEND config, check CONFIG_XEN_BACKEND, and check the BACKEND config as you need:
 
CONFIG_XEN_BLKDEV_BACKEND=y
 
CONFIG_XEN_NETDEV_BACKEND=y
 
   
  +
Start from the multi_v7_defconfig multiplatform kernel:
or use sunxi dom0 kernel directly
 
git clone -b sun7i-xen-dom0 https://github.com/bjzhang/linux-allwinner.git sun7i-xen-dom0
 
cd sun7i-xen-dom0
 
 
make sun7i_dom0_defconfig
 
make sun7i_dom0_defconfig
  +
  +
From here you will want to enable the various Xen options (CONFIG_XEN, frontend and backend drivers etc, see [[Mainline_Linux_Kernel_Configs]] for more general details).
  +
  +
Then:
 
make zImage
 
make zImage
 
make dtbs
 
make dtbs
   
The device tree is located in arch/arm/boot/dts/sun7i-a20-cubieboard2-xen.dtb
+
The final kernel binary will be in `arch/arm/boot/zImage` and the device tree will be located in in `arch/arm/boot/dts` e.g. sun7i-a20-cubieboard2.dtb, sun7i-a20-cubietruck.dtb etc.
  +
  +
The same kernel image should work for both dom0 and domU.
   
 
== Building Xen ==
 
== Building Xen ==
   
the lastest xen should work. reference [[Xen_ARMv7_with_Virtualization_Extensions#Building_Xen_on_ARM|Build Xen on ARM]] and [[Xen_ARMv7_with_Virtualization_Extensions#Building Xen and Linux Dom0|Building Xen and Linux Dom0]] for building xen and generating the xen-uImage.
+
The latest xen should work. See [[Xen_ARMv7_with_Virtualization_Extensions#Building_Xen_on_ARM|Build Xen on ARM]] and [[Xen_ARMv7_with_Virtualization_Extensions#Building Xen and Linux Dom0|Building Xen and Linux Dom0]] for building xen and generating the xen-uImage.
i test pass on xen commit 720f45ad: Julien Grall, xen/evtchn: Fix build on ARM
 
   
use the following build command for enable early printk for a20:
+
Use the following build command for enable early printk for a20:
make dist-xen XEN_TARGET_ARCH=arm32 CROSS_COMPILE=arm-linux-gnueabihf- CONFIG_EARLY_PRINTK=sun7i CONFIG_DTB_FILE=/path/to/sun7i-a20-cubieboard2-xen.dtb
+
make dist-xen XEN_TARGET_ARCH=arm32 CROSS_COMPILE=arm-linux-gnueabihf- CONFIG_EARLY_PRINTK=sun7i
and generate the xen image, note that sunxi ddr base physical base address is 0x40000000, do not use 0x80000000 for base address as other platform.
 
mkimage -A arm -T kernel -a 0x40200000 -e 0x40200000 -C none -d "xen/xen" xen-uImage
 
   
== Building linux DomU ==
+
== Booting Xen and Dom0 ==
   
  +
To boot Xen and Dom0, you can use USB boot or sd boot. Some runtime manipulation of the DTB is needed, but the basic outline is the same in each case (only the method to load the binary differs).
xen domU kernel is supported by upstream. and remember that domU guest do not aware of which hardware it running on, it only know about the mach-virt.
 
if you want to a domU kernel, you need to ucheck all the BACKEND config and check the FRONTEND config as you need:
 
CONFIG_XEN_BLKDEV_FRONTEND=y
 
CONFIG_XEN_NETDEV_FRONTEND=y
 
CONFIG_HVC_XEN_FRONTEND=y
 
CONFIG_XEN_FBDEV_FRONTEND=y
 
note that '''CONFIG_XEN_XENBUS_FRONTEND''' will be automatically checked by any FRONTEND driver.
 
   
  +
# SUNXI Xen Boot Script
currenly, xen directly use the dom0 gic dist base and cpu base as domU gic dist and cpu base. reference gicv_setup() in xen/arch/arm/gic.c for details.
 
  +
for sunxi, need chances the followings: (this patch is included in my branch)
 
  +
setenv fdt_addr 0x43000000
  +
setenv xen_addr_r 0x44000000
  +
setenv kernel_addr_r 0x47000000
  +
  +
# Load xen/xen to ${xen_addr_r}
  +
setenv bootargs "console=dtuart dtuart=/soc@01c00000/serial@01c28000 dom0_mem=128M"
  +
  +
# Load appropriate .dtb file to ${fdt_addr}
  +
  +
fdt addr ${fdt_addr} 0x40000
  +
  +
fdt resize
  +
  +
fdt chosen
  +
  +
fdt set /chosen \#address-cells <1>
  +
fdt set /chosen \#size-cells <1>
  +
  +
# Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
  +
  +
fdt mknod /chosen module@0
  +
fdt set /chosen/module@0 compatible "xen,linux-zimage" "xen,multiboot-module"
  +
fdt set /chosen/module@0 reg <${kernel_addr_r} 0x${filesize} >
  +
fdt set /chosen/module@0 bootargs "console=hvc0 ro root=/dev/sda1 clk_ignore_unused"
  +
  +
bootz ${xen_addr_r} - ${fdt_addr}
   
  +
The easiest approach is to create a file (boot.xen) with this and then convert this into a u-boot boot.scr with:
diff --git a/arch/arm/boot/dts/xenvm-4.2.dts b/arch/arm/boot/dts/xenvm-4.2.dts
 
index 3369151..5d5689e 100644
 
--- a/arch/arm/boot/dts/xenvm-4.2.dts
 
+++ b/arch/arm/boot/dts/xenvm-4.2.dts
 
@@ -50,13 +50,13 @@
 
reg = <0 0x80000000 0 0x08000000>;
 
};
 
 
- gic: interrupt-controller@2c001000 {
 
+ gic: interrupt-controller@1c81000{
 
compatible = "arm,cortex-a15-gic", "arm,cortex-a9-gic";
 
#interrupt-cells = <3>;
 
#address-cells = <0>;
 
interrupt-controller;
 
- reg = <0 0x2c001000 0 0x1000>,
 
- <0 0x2c002000 0 0x100>;
 
+ reg = <0 0x01c81000 0 0x1000>,
 
+ <0 0x01c82000 0 0x1000>;
 
};
 
 
timer {
 
   
  +
mkimage -A arm -T script -d boot.xen boot.scr.
it should not need to change after ian auto-generate dts patch upstreamed.
 
   
  +
This can then be loaded to address 0x41000000 and then launched with:
git clone -b sun7i_xen_domU https://github.com/bjzhang/linux-allwinner.git sun7i_xen_domU
 
cd sun7i_xen_domU
 
make sun7i_domU_defconfig
 
make zImage
 
make dtbs
 
 
== Booting Xen and Dom0 ==
 
   
  +
source 0x41000000
To boot Xen and Dom0, you can use USB boot or sd boot.
 
   
 
=== Booting via PXE ===
 
=== Booting via PXE ===
  +
TODO
 
  +
To boot use the boot.scr above loading images with:
  +
  +
tftp ${address} /path/to/image
  +
  +
For example:
  +
  +
# Load xen/xen to ${xen_addr_r}
  +
tftp ${xen_addr_r} /cubieboard/xen
  +
  +
# Load appropriate .dtb file to ${fdt_addr}
  +
tftp ${fdt_addr} /cubieboard/sun7i-a20-cubieboard2.dtb
  +
  +
# Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
  +
tftp ${kernel_addr_r} /cubieboard/vmlinuz
  +
  +
To boot this set bootcmd:
  +
  +
setenv bootcmd setenv autoload no\;dhcp\;tftp 0x41000000 /boot.scr;source 0x41000000
  +
saveenv
  +
boot
   
 
=== Booting via USBBoot(FEL) ===
 
=== Booting via USBBoot(FEL) ===
  +
reference: http://linux-sunxi.org/FEL/USBBoot
 
  +
reference: http://linux-sunxi.org/FEL/USBBoot
  +
  +
Arrange for all of the images to be loaded at the appropriate addresses via the FEL utility and then load a suitable boot.scr to launch them.
   
 
=== Booting directly on the SD card ===
 
=== Booting directly on the SD card ===
  +
 
reference [http://linux-sunxi.org/Bootable_SD_card] for how to make a bootable sdcard.
 
reference [http://linux-sunxi.org/Bootable_SD_card] for how to make a bootable sdcard.
   
* Copy xen-uImage, zImage and the initrd the root directory of you SD card.
+
Copy xen, zImage, the dtb and boot.scr to the root directory of you SD card.
  +
* save the bootcmd
 
  +
To boot use the boot.scr above loading images with:
setenv bootcmd "fatload mmc 0 45000000 xen-uImage; fatload mmc 0 50000000 zImage; fatload mmc 0 60000000 initrd; bootm 45000000"
 
  +
savenv
 
  +
fatload mmc 0 ${address} /path/to/image
* boot
 
  +
boot
 
  +
For example:
  +
  +
# Load xen/xen to ${xen_addr_r}
  +
fatload mmc 0 ${xen_addr_r} /xen
  +
  +
# Load appropriate .dtb file to ${fdt_addr}
  +
fatload mmc 0 ${fdt_addr} /sun7i-a20-cubieboard2.dtb
  +
  +
# Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
  +
fatload mmc 0 ${kernel_addr_r} /vmlinuz
  +
  +
To boot set the bootcmd:
  +
  +
setenv bootcmd "fatload mmc 0 0x41000000 boot.scr; source 0x41000000"
  +
savenv
  +
boot
  +
  +
This assume the SD card has only 1 partition with '''fat''' filesystem. Use e.g. ext2load etc if this is not the case.
  +
  +
=== Mount NFS after initrd boot ===
   
  +
Using a [http://download.opensuse.org/repositories/devel:/ARM:/12.3:/Contrib:/sunxi/images/openSUSE-12.3-ARM-JeOS-rootfs.armv7l-1.12.1-Build71.1.tbz distrbution] is easily to compile xen tools.
Assume the SD card has only 1 partition with '''fat''' filesystem.
 
   
  +
Both opensuse arm 12.3 rootfs and Debian have been used by developers. Other distribution which support armhf is ok too.
== Mount NFS after initrd boot ==
 
Using a [http://download.opensuse.org/repositories/devel:/ARM:/12.3:/Contrib:/sunxi/images/openSUSE-12.3-ARM-JeOS-rootfs.armv7l-1.12.1-Build71.1.tbz distrbution] is easily to compile xen tools. i use opensuse arm 12.3 rootfs for it. other distribution which support armhf is ok too.
 
   
 
== Create domU ==
 
== Create domU ==
Line 143: Line 181:
 
;domU config example
 
;domU config example
 
> cat domU_test
 
> cat domU_test
kernel = "/root/domU/zImage_dtb"
+
kernel = "/root/domU/zImage
 
memory = "128"
 
memory = "128"
 
name = "domU"
 
name = "domU"
Line 160: Line 198:
   
 
== DomU kernel debug ==
 
== DomU kernel debug ==
  +
xen support varity debug method. you could use xl debug-keys for dumping information. use xen_raw_console_write for output DomU kernel output.
 
  +
Xen supports a variety of debug methods. You can use xl debug-keys for dumping information. Use `xen_raw_console_write` for output DomU kernel output.
but gdbsx is not work for arm right now.
 
  +
  +
`gdbsx` is not work for arm right now.
   
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
 
diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
Line 187: Line 227:
 
[http://linux-sunxi.org/ allwinner sunxi resources]
 
[http://linux-sunxi.org/ allwinner sunxi resources]
 
[http://lists.xen.org/archives/html/xen-devel/2013-08/msg03040.html]
 
[http://lists.xen.org/archives/html/xen-devel/2013-08/msg03040.html]
 
== Known Issue ==
 
without [http://lists.xen.org/archives/html/xen-devel/2013-09/msg02232.html sunxi platform patch], there is a warning during xen boot:
 
(XEN) WARNING: Unrecognized/unsupported device tree compatible list
 
(XEN) Available platform support:
 
(XEN) - VERSATILE EXPRESS
 
(XEN) - SAMSUNG EXYNOS5
 
(XEN) - CALXEDA MIDWAY
 
(XEN) - TI OMAP5
 
   
 
[[Category:XenARM]]
 
[[Category:XenARM]]

Revision as of 11:57, 14 January 2014

Hardware

This wiki talks about Xen on Allwinner A20(Cortex-A7 dual core, code name sun7i).

The A31(Cortex-A7 quad core, code name sun6i) should work as well, but has not been as widely tested.

The following boards have been tested:

  • A20
    • Cubieboard2 (note that the original Cubieboard does not support virtualisation)
    • Cubietruck (AKA Cubieboard 3)

Bootloader

As described in Firmware Requirements, Xen need boot from non-secure hyper mode.

Source Code

sunxi support is not currently merged into mainline u-boot. Support for this platform is available in the u-boot-sunxi.git tree

Hans de Goede maintains a branch which adds the necessary support for PSCI to enable SMP support and booting from non-secure hypervisor mode. See https://github.com/jwrdegoede/u-boot-sunxi, branch `sunxi-next`.

Compile

See [1] for more details on building U-boot for sunxi.

For sd card:

   make Cubieboard2 CROSS_COMPILE=arm-linux-gnueabihf- -j8

For USB/FEL boot:

   make Cubieboard2_FEL CROSS_COMPILE=arm-linux-gnueabihf- -j8

Linux

Upstream Community

Support for the Allwinner processors in Linux is mainly a community effort, see the Linux Sunxi Wiki.

Source Code

Upstream Linux support for Allwinner processors is a work in progress. See Sunxi Linux mainlining effort for current status.

As of 3.13-rc6 there is a lot of useful support in the mainline kernel, however the following are not present:

  • SATA AHCI support
  • MMC support
  • USB support

Support for these can be found in the sunxi linux tree at https://github.com/linux-sunxi/linux-sunxi. The `sunxi-next` contain stuff destined for the next Linux merge window, while `sunxi-devel` contains things targeting future versions. Both branches are rebasing.

Building

Start from the multi_v7_defconfig multiplatform kernel:

 make sun7i_dom0_defconfig

From here you will want to enable the various Xen options (CONFIG_XEN, frontend and backend drivers etc, see Mainline_Linux_Kernel_Configs for more general details).

Then:

 make zImage
 make dtbs

The final kernel binary will be in `arch/arm/boot/zImage` and the device tree will be located in in `arch/arm/boot/dts` e.g. sun7i-a20-cubieboard2.dtb, sun7i-a20-cubietruck.dtb etc.

The same kernel image should work for both dom0 and domU.

Building Xen

The latest xen should work. See Build Xen on ARM and Building Xen and Linux Dom0 for building xen and generating the xen-uImage.

Use the following build command for enable early printk for a20:

   make dist-xen XEN_TARGET_ARCH=arm32 CROSS_COMPILE=arm-linux-gnueabihf- CONFIG_EARLY_PRINTK=sun7i

Booting Xen and Dom0

To boot Xen and Dom0, you can use USB boot or sd boot. Some runtime manipulation of the DTB is needed, but the basic outline is the same in each case (only the method to load the binary differs).

   # SUNXI Xen Boot Script
   
   setenv fdt_addr      0x43000000
   setenv xen_addr_r    0x44000000
   setenv kernel_addr_r 0x47000000
   
   # Load xen/xen to ${xen_addr_r}
   setenv bootargs "console=dtuart dtuart=/soc@01c00000/serial@01c28000 dom0_mem=128M"
   
   # Load appropriate .dtb file to ${fdt_addr}
   
   fdt addr ${fdt_addr} 0x40000
   
   fdt resize
   
   fdt chosen
   
   fdt set /chosen \#address-cells <1>
   fdt set /chosen \#size-cells <1>
   
   # Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
   
   fdt mknod /chosen module@0
   fdt set /chosen/module@0 compatible "xen,linux-zimage" "xen,multiboot-module"
   fdt set /chosen/module@0 reg <${kernel_addr_r} 0x${filesize} >
   fdt set /chosen/module@0 bootargs "console=hvc0 ro root=/dev/sda1 clk_ignore_unused"
   
   bootz ${xen_addr_r} - ${fdt_addr}

The easiest approach is to create a file (boot.xen) with this and then convert this into a u-boot boot.scr with:

   mkimage -A arm -T script -d boot.xen boot.scr.

This can then be loaded to address 0x41000000 and then launched with:

   source 0x41000000

Booting via PXE

To boot use the boot.scr above loading images with:

   tftp ${address} /path/to/image

For example:

    # Load xen/xen to ${xen_addr_r}
    tftp ${xen_addr_r} /cubieboard/xen
   
    # Load appropriate .dtb file to ${fdt_addr}
    tftp ${fdt_addr} /cubieboard/sun7i-a20-cubieboard2.dtb
   
    # Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
    tftp ${kernel_addr_r} /cubieboard/vmlinuz

To boot this set bootcmd:

   setenv bootcmd setenv autoload no\;dhcp\;tftp 0x41000000 /boot.scr;source 0x41000000
   saveenv
   boot

Booting via USBBoot(FEL)

reference: http://linux-sunxi.org/FEL/USBBoot

Arrange for all of the images to be loaded at the appropriate addresses via the FEL utility and then load a suitable boot.scr to launch them.

Booting directly on the SD card

reference [2] for how to make a bootable sdcard.

Copy xen, zImage, the dtb and boot.scr to the root directory of you SD card.

To boot use the boot.scr above loading images with:

   fatload mmc 0 ${address} /path/to/image

For example:

   # Load xen/xen to ${xen_addr_r}
   fatload mmc 0 ${xen_addr_r} /xen
   
   # Load appropriate .dtb file to ${fdt_addr}
   fatload mmc 0 ${fdt_addr} /sun7i-a20-cubieboard2.dtb
   
   # Load Linux arch/arm/boot/zImage to ${kernel_addr_r}
   fatload mmc 0 ${kernel_addr_r} /vmlinuz

To boot set the bootcmd:

   setenv bootcmd "fatload mmc 0 0x41000000 boot.scr; source 0x41000000"
   savenv
   boot

This assume the SD card has only 1 partition with fat filesystem. Use e.g. ext2load etc if this is not the case.

Mount NFS after initrd boot

Using a distrbution is easily to compile xen tools.

Both opensuse arm 12.3 rootfs and Debian have been used by developers. Other distribution which support armhf is ok too.

Create domU

setup the harddisk
   losetup /dev/loop0 /root/domU/rootfs.ext3 
domU config example
   > cat domU_test
   kernel = "/root/domU/zImage
   memory = "128" 
   name = "domU" 
   vcpus = 1 
   serial="pty"
   disk = [ 'phy:/dev/loop0,xvda,w' ]
   vif=[ 'mac=00:16:3e:56:af:69,bridge=virbr0,type=netfront', ]
create
   xl create domU_test

or enable all the debug message

   xl -vvv create -d domU_testa
connect to console

xl console domU_test

DomU kernel debug

Xen supports a variety of debug methods. You can use xl debug-keys for dumping information. Use `xen_raw_console_write` for output DomU kernel output.

`gdbsx` is not work for arm right now.

   diff --git a/kernel/printk/printk.c b/kernel/printk/printk.c
   index b4e8500..060c163 100644
   --- a/kernel/printk/printk.c
   +++ b/kernel/printk/printk.c
   @@ -1488,6 +1488,7 @@ static size_t cont_print_text(char *text, size_t size)
       return textlen;
    }
    
   +#include <xen/hvc-console.h>
    asmlinkage int vprintk_emit(int facility, int level,
                   const char *dict, size_t dictlen,
                   const char *fmt, va_list args)
   @@ -1546,6 +1547,7 @@ asmlinkage int vprintk_emit(int facility, int level,
        * prefix which might be passed-in as a parameter.
        */
       text_len = vscnprintf(text, sizeof(textbuf), fmt, args);
   +    xen_raw_console_write(text);
    
       /* mark and strip a trailing newline */
       if (text_len && text[text_len-1] == '\n') {

Resources

allwinner sunxi resources [3]