Hi,

On 09/05/2016 11:36 AM, Zhe Zhao wrote:

Hi,

Thanks for your answers, I really appreciate it.

I tried to run L4Linux and L4Re in a qemu environment, is it support SMP already? I found I only have a single core L4Linux running. and Fiasco report only one scheduler instance.

Yes, SMP is supported. Have you configured the L4Re microkernel with multiprocessing support? Did you start qemu with multiple CPUs? To enable more CPUs in L4Linux you need to pass the 'l4x_cpus=<VALUE>' parameter on the cmdline.

And is it possible to direct reuse the L4Linux's driver instead of rewrite them in L4Re? is that IO manager used to mapping all needed device physical address to L4Linux's memory space? Is that mean I can map all device direct to L4Linux through IO manager?

Yes, but there might be work involved. First you should make yourself familiar with the concepts of Io [0].

Is there any work ongoing to support ARM64 on L4Re and L4Linux? It will be quite interesting consider most of the ARM device are moving to be 64 bit arch.

We are looking at it but there is nothing to announce publicly right now

Do you have some recommend documents for the newbie like me to get a quick start up?

The L4Re documentation [1].

Matthias.

[0] http://l4re.org/doc/io.html [1] http://l4re.org/doc/

Br Alex

2016-09-02 14:24 GMT+08:00 Matthias Lange <matthias.lange@kernkonzept.com mailto:matthias.lange@kernkonzept.com>:

Hi,

On 08/31/2016 02:35 PM, Zhe Zhao wrote:
> Hi,
>
> After read the basic ideas of L4Linux I have some questions related to it.
>
> Is L4Linux run as a paravirtualization VM on L4Re? Then the traditional
> Linux Process just still compiled against Linux system and put them
> together with L4Linux disk image?
> so it means L4Re works like qemu and Linuxl?

No, L4Re does not work like qemu.

> or L4Re works as a micro kernel operating system, and L4Linux run as a
> process on it, all devices handled to L4Linux to reuse the drivers of
> L4Linux? and the previous Linux process
> compiled with Linux, but run direct on L4Re as L4 processes which
> communicate with L4Linux through IPC?

L4Linux is a modified version of the Linux kernel with the hardware
abstraction layer (HAL) implemented using L4Re primitives. Technically
L4Re appears to be "just" another hardware architecture for the Linux
kernel, just like ARM or MIPS.

L4Linux runs as a user space task on top of the L4Re microkernel and at
the (Linux) kernel ABI is unmodified which allows to run existing Linux
programs. That means, you can compile "normal" Linux programs with your
standard tool chain, put the binary onto a ramdisk or disk image and run
it with L4Linux.

> it is quite confused after read a little of the codes, in L4Linux, seems
> there is some injection of L4 task stuffs inside thread_struct of Linux,
> but also have some vCPU related stuffs,
> can you help me about what is the real behavior of L4Linux?

Each (Linux) process is actually an L4Re task with the exception and
page fault handler set to the L4Linux task. That's why some L4-specific
additions are required to Linux kernel data structures.

Matthias.

> I'm sorry to ask this basic questions, but after some digging I feel
> quite confused about how it works.
>
> Thanks
> Br
> Alex

Hi,

On 09/07/2016 09:00 AM, Zhe Zhao wrote:

Hi,

Thanks for you answers.

Does Fiasco use the scheduler that follow the priority? I mean like if there is high priority task, it will always have CPU?

I would like to point you to this recent thread on the mailing list which discusses details about L4Re's scheduling [1].

Does Fiasco already support tickless kernel? or it will use a fixed 1000 HZ as the tick?

There is some support for tickless/oneshot mode in the L4Re microkernel but it is not tested.

I'd like to run L4Linux on a Droid-xu4 or raspberry is there any easy start guide for it?

Unfortunately no. But it is not complicated either. You can take the L4Linux basic example as a starting point. You need to build the L4Re microkernel for the right platform. The userland needs to be compiled for the right ARM architecture (Rasperry Pi is ARM6k whereas the Droid is ARMv7). Then you create an uImage which you can e.g. boot via tftp.

When I tried the L4Linux with ramdisk which in the L4Re snapshot, it seems the it just like running a Linux. I don't know if below understanding is correct, if not please correct me

The syscall fork "int 80" will be redirect to L4Linux from Fiasco by IPC (how Fiasco knows to redirect int 80 through IPC to L4Linux?), and fork will be executed inside L4Linux, then L4Linux will create Fiasco task? (so here we have two task proc combined to identify one linux process), and L4Linux will create vmspace for the process ? then how the memory space be handled to Fiasco?

L4-like systems have the concept of an exception handler per thread. For L4Linux this means that all exceptions triggered by a Linux user process are send to the L4Linux kernel.

In the case of fork() the L4Linux kernel eventually creates a new L4 task (l4_factory_create_task). Memory gets mapped from the L4Linux task into the new task e.g. upon pagefaults.

From the above assumption, it means I can just build a rootfs with native Linux apps, and use IO manager to pass the harddisk/emmc to L4Linux, then I can run whatever apps I like?

Basically yes. On ARM platforms there are some stumbling blocks for sure as device pass-through can be tricky at times.

I'd like to start read codes related to Fiasco, L4Re, any suggestions about the start point?

That's a very generic question and the generic answer for the L4Re microkernel is: fiasco/src/kern. Do you have any specific mechanisms in mind you want to understand?

Matthias.

[1] http://os.inf.tu-dresden.de/pipermail/l4-hackers/2016/007907.html

Br Alex

2016-09-06 23:37 GMT+08:00 Matthias Lange <matthias.lange@kernkonzept.com mailto:matthias.lange@kernkonzept.com>:

Hi,

On 09/05/2016 11:36 AM, Zhe Zhao wrote:
> Hi,
>
> Thanks for your answers, I really appreciate it.
>
> I tried to run L4Linux and L4Re in a qemu environment, is it support SMP
> already? I found I only have a single core L4Linux running. and Fiasco
> report only one scheduler instance.

Yes, SMP is supported. Have you configured the L4Re microkernel with
multiprocessing support? Did you start qemu with multiple CPUs? To
enable more CPUs in L4Linux you need to pass the 'l4x_cpus=<VALUE>'
parameter on the cmdline.

> And is it possible to direct reuse the L4Linux's driver instead of
> rewrite them in L4Re? is that IO manager used to mapping all needed
> device physical address to L4Linux's memory space? Is that mean I can map
> all device direct to L4Linux through IO manager?

Yes, but there might be work involved. First you should make yourself
familiar with the concepts of Io [0].

> Is there any work ongoing to support ARM64 on L4Re and L4Linux? It will
> be quite interesting consider most of the ARM device are moving to be 64
> bit arch.

We are looking at it but there is nothing to announce publicly right now

> Do you have some recommend documents for the newbie like me to get a
> quick start up?

The L4Re documentation [1].


Matthias.

[0] http://l4re.org/doc/io.html
[1] http://l4re.org/doc/

> Br
> Alex
>
> 2016-09-02 14:24 GMT+08:00 Matthias Lange
> <matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>
<mailto:matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>>>:
>
>     Hi,
>
>     On 08/31/2016 02:35 PM, Zhe Zhao wrote:
>     > Hi,
>     >
>     > After read the basic ideas of L4Linux I have some questions
related to it.
>     >
>     > Is L4Linux run as a paravirtualization VM on L4Re? Then the
traditional
>     > Linux Process just still compiled against Linux system and
put them
>     > together with L4Linux disk image?
>     > so it means L4Re works like qemu and Linuxl?
>
>     No, L4Re does not work like qemu.
>
>     > or L4Re works as a micro kernel operating system, and
L4Linux run as a
>     > process on it, all devices handled to L4Linux to reuse the
drivers of
>     > L4Linux? and the previous Linux process
>     > compiled with Linux, but run direct on L4Re as L4 processes
which
>     > communicate with L4Linux through IPC?
>
>     L4Linux is a modified version of the Linux kernel with the
hardware
>     abstraction layer (HAL) implemented using L4Re primitives.
Technically
>     L4Re appears to be "just" another hardware architecture for
the Linux
>     kernel, just like ARM or MIPS.
>
>     L4Linux runs as a user space task on top of the L4Re
microkernel and at
>     the (Linux) kernel ABI is unmodified which allows to run
existing Linux
>     programs. That means, you can compile "normal" Linux programs
with your
>     standard tool chain, put the binary onto a ramdisk or disk
image and run
>     it with L4Linux.
>
>     > it is quite confused after read a little of the codes, in
L4Linux, seems
>     > there is some injection of L4 task stuffs inside
thread_struct of Linux,
>     > but also have some vCPU related stuffs,
>     > can you help me about what is the real behavior of L4Linux?
>
>     Each (Linux) process is actually an L4Re task with the
exception and
>     page fault handler set to the L4Linux task. That's why some
L4-specific
>     additions are required to Linux kernel data structures.
>
>     Matthias.
>
>     > I'm sorry to ask this basic questions, but after some
digging I feel
>     > quite confused about how it works.

Hi,

On 09/09/2016 11:49 AM, Zhe Zhao wrote:

Hi,

Majorly I'd like to run a Android M with L4Linux on my ODROID-XU4, board, but I'm not sure is that possible, seems there is a L4Android already, but it is running on a qemu with strange two androids run together.

Is there similiar project in your side, and is that a good idea to run Android on L4Linux, if I understand it correct, I just need to port needed linux driver to L4Linux, and build a native google android, then it should work?

Running Android in a virtualized environment is a tough task. Unfortunately it is not "just" about porting drivers to L4Linux. Device pass-through is a tricky thing. If you still want to pursue this endeavour a good start is to build a generic ARM version of Android from the AOSP. Then take the disk images, create a L4Re configuration and try to boot the system.

Matthias.

I want to achieve Android together with a subsystem can achieve hard real time, instead of using weird VM solutions.

Thanks Br Alex

2016-09-09 14:27 GMT+08:00 Matthias Lange <matthias.lange@kernkonzept.com mailto:matthias.lange@kernkonzept.com>:

Hi,

On 09/07/2016 09:00 AM, Zhe Zhao wrote:
> Hi,
>
> Thanks for you answers.
>
> Does Fiasco use the scheduler that follow the priority? I mean like if
> there is high priority task, it will always have CPU?

I would like to point you to this recent thread on the mailing list
which discusses details about L4Re's scheduling [1].

> Does Fiasco already support tickless kernel? or it will use a fixed 1000
> HZ as the tick?

There is some support for tickless/oneshot mode in the L4Re microkernel
but it is not tested.

> I'd like to run L4Linux on a Droid-xu4 or raspberry is there any easy
> start guide for it?

Unfortunately no. But it is not complicated either. You can take the
L4Linux basic example as a starting point. You need to build the L4Re
microkernel for the right platform. The userland needs to be compiled
for the right ARM architecture (Rasperry Pi is ARM6k whereas the Droid
is ARMv7). Then you create an uImage which you can e.g. boot via tftp.

> When I tried the L4Linux with ramdisk which in the L4Re snapshot, it
> seems the it just like running a Linux. I don't know if below
> understanding is correct, if not please correct me
>
> The syscall fork "int 80" will be redirect to L4Linux from Fiasco by IPC
> (how Fiasco knows to redirect int 80 through IPC to L4Linux?), and fork
> will be executed inside L4Linux, then L4Linux will create Fiasco task?
>  (so here we have two task proc combined to identify one linux process),
> and L4Linux will create vmspace for the process ? then how the memory
> space be handled to Fiasco?

L4-like systems have the concept of an exception handler per thread. For
L4Linux this means that all exceptions triggered by a Linux user process
are send to the L4Linux kernel.

In the case of fork() the L4Linux kernel eventually creates a new L4
task (l4_factory_create_task). Memory gets mapped from the L4Linux task
into the new task e.g. upon pagefaults.

> From the above assumption, it means I can just build a rootfs with
> native Linux apps, and use IO manager to pass the harddisk/emmc to
> L4Linux, then I can run whatever apps I like?

Basically yes. On ARM platforms there are some stumbling blocks for sure
as device pass-through can be tricky at times.

> I'd like to start read codes related to Fiasco, L4Re, any suggestions
> about the start point?

That's a very generic question and the generic answer for the L4Re
microkernel is: fiasco/src/kern. Do you have any specific mechanisms in
mind you want to understand?

Matthias.


[1]
http://os.inf.tu-dresden.de/pipermail/l4-hackers/2016/007907.html
<http://os.inf.tu-dresden.de/pipermail/l4-hackers/2016/007907.html>

>
> Br
> Alex
>
>
> 2016-09-06 23:37 GMT+08:00 Matthias Lange
> <matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>
<mailto:matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>>>:
>
>     Hi,
>
>     On 09/05/2016 11:36 AM, Zhe Zhao wrote:
>     > Hi,
>     >
>     > Thanks for your answers, I really appreciate it.
>     >
>     > I tried to run L4Linux and L4Re in a qemu environment, is it
support SMP
>     > already? I found I only have a single core L4Linux running.
and Fiasco
>     > report only one scheduler instance.
>
>     Yes, SMP is supported. Have you configured the L4Re
microkernel with
>     multiprocessing support? Did you start qemu with multiple CPUs? To
>     enable more CPUs in L4Linux you need to pass the
'l4x_cpus=<VALUE>'
>     parameter on the cmdline.
>
>     > And is it possible to direct reuse the L4Linux's driver
instead of
>     > rewrite them in L4Re? is that IO manager used to mapping all
needed
>     > device physical address to L4Linux's memory space? Is that
mean I can map
>     > all device direct to L4Linux through IO manager?
>
>     Yes, but there might be work involved. First you should make
yourself
>     familiar with the concepts of Io [0].
>
>     > Is there any work ongoing to support ARM64 on L4Re and
L4Linux? It will
>     > be quite interesting consider most of the ARM device are
moving to be 64
>     > bit arch.
>
>     We are looking at it but there is nothing to announce publicly
right now
>
>     > Do you have some recommend documents for the newbie like me
to get a
>     > quick start up?
>
>     The L4Re documentation [1].
>
>
>     Matthias.
>
>     [0] http://l4re.org/doc/io.html
>     [1] http://l4re.org/doc/
>
>     > Br
>     > Alex
>     >
>     > 2016-09-02 14:24 GMT+08:00 Matthias Lange
>     > <matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>
>     <mailto:matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>>
>     <mailto:matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>
>     <mailto:matthias.lange@kernkonzept.com
<mailto:matthias.lange@kernkonzept.com>>>>:
>     >
>     >     Hi,
>     >
>     >     On 08/31/2016 02:35 PM, Zhe Zhao wrote:
>     >     > Hi,
>     >     >
>     >     > After read the basic ideas of L4Linux I have some
questions
>     related to it.
>     >     >
>     >     > Is L4Linux run as a paravirtualization VM on L4Re?
Then the
>     traditional
>     >     > Linux Process just still compiled against Linux system and
>     put them
>     >     > together with L4Linux disk image?
>     >     > so it means L4Re works like qemu and Linuxl?
>     >
>     >     No, L4Re does not work like qemu.
>     >
>     >     > or L4Re works as a micro kernel operating system, and
>     L4Linux run as a
>     >     > process on it, all devices handled to L4Linux to reuse the
>     drivers of
>     >     > L4Linux? and the previous Linux process
>     >     > compiled with Linux, but run direct on L4Re as L4
processes
>     which
>     >     > communicate with L4Linux through IPC?
>     >
>     >     L4Linux is a modified version of the Linux kernel with the
>     hardware
>     >     abstraction layer (HAL) implemented using L4Re primitives.
>     Technically
>     >     L4Re appears to be "just" another hardware architecture for
>     the Linux
>     >     kernel, just like ARM or MIPS.
>     >
>     >     L4Linux runs as a user space task on top of the L4Re
>     microkernel and at
>     >     the (Linux) kernel ABI is unmodified which allows to run
>     existing Linux
>     >     programs. That means, you can compile "normal" Linux
programs
>     with your
>     >     standard tool chain, put the binary onto a ramdisk or disk
>     image and run
>     >     it with L4Linux.
>     >
>     >     > it is quite confused after read a little of the codes, in
>     L4Linux, seems
>     >     > there is some injection of L4 task stuffs inside
>     thread_struct of Linux,
>     >     > but also have some vCPU related stuffs,
>     >     > can you help me about what is the real behavior of
L4Linux?
>     >
>     >     Each (Linux) process is actually an L4Re task with the
>     exception and
>     >     page fault handler set to the L4Linux task. That's why some
>     L4-specific
>     >     additions are required to Linux kernel data structures.
>     >
>     >     Matthias.
>     >
>     >     > I'm sorry to ask this basic questions, but after some
>     digging I feel
>     >     > quite confused about how it works.