Re: [gentoo-dev] [GSoC2012] Cross Container Support Project

[Alexey Shvetsov]

Hi!

Well i have 2 arm lxc containers on amd64 machine. Its works good if 
qemu support most of needed cross arch instructions

Jing Huang писал 2012-03-23 13:36:
> Hi Everyone,
>
> I am a student at Peking University in China. I am very interested in
> the project of Cross Container Support(). I have some ideas about the
> project. Please help me to examine the thoughts.
>
> First, I think downloading stage and portage packets into specified
> directory each time needs to be impoved(). It needs to build
> execution
> environment every time. So it is not convenient. On the other hand,
> the files in specified directory would be modified by some process
> potentially. It is not an isolated execution environment at all.
> Therefore, I would make some img files for the each arch, including
> arm, mips, etc. The img file contains arch-stage and portage. When
> creating the qemu-user container, the iniscript mounts the img file
> into specified directory then chroot to it.
>
> Second, if the process accesses disk frequently, I would to make a
> tmpfs file for the qemu-user container. The process in the container
> is running on tmpfs file and been sped up.
>
> Third, I would custom a lightweight qemu-user container for the
> specified process if necessary. In my previous work, I made a custom
> ramdisk VM for the process by modifying the mkinitrd script. With the
> help of “ldd –v ” command, I could get the shared libraries of
> the process and packet them into ramdisk. But in Gentoo, maybe I
> could
> custom the qemu-user container using the USE label.
>
> In my proposal, this project uses a small quantity of bash to
> implement just the core tools (create, destroy, enter). In simpler
> terms, I plan to implement them in this way:
>
> 1. create routine
>
> # qemu_container_create config_file
>
>  The config_file specifies arch, arch-img file, chroot directory,
> additional args of qemu(like "-cpu cortex-a8"). Then the create
> routine will execute as:
>
>  1). If having the arch-img then mount it into chroot directory.
>
>  2). If not, make a new img file, download stageball&portage, unpack
> them to the chroot directory.
>
>  2). modprobe binfmt_misc and register the qemu-user-arch to the
> binfmt_misc.
>
>  3). install the static qemu-user into the chroot directory and mount
> the required directories.
>
>  4). register this new container to our managment tool. The register
> info includes container_id, stageball version, stageball arch, chroot
> directory, etc.
>
> 2. enter routine
>
> #qemu_container_enter container_id
>
>  The enter routine opens a terminal and chroot into the environment.
> The management tool should also set the container is in "running"
> state.
>
> 3. destroy routine
>
> #qemu_container_destroy container_id
>
>  1). exits from chroot environment
>
>  2). unmount stuff when not in use
>
>  3). clear the qemu-user-arch in binfmt_misc register file (maybe
> other containers use it)
>
>  4). remove the container info from managment tool
>
> Besides these routines, I would also implement container_list and
> container_export routines. The former lists the info/state of
> containers. The latter is used to export system images.
>
> Questions:
>
> 1). Why integrate qemu-user container with crossdev? Crossdev is a
> cross compiler. The qemu-user container not only compiles the
> heterogeneous programs but also tests them. I thought if the
> qemu-user
> container was good enough, it could replace the crossdev.
>
> 2). "An additional task is to support layered systems so native
> userspace can be used to further speed up the process (hybrid
> chroot)." I don't very understand the task. Could someone help me and
> explain the “hybrid chroot”?
>
> Would someone give me some suggestions? Any comments will be much
> appreciated.
>
> Jing Huang.

-- 
Best Regards,
Alexey 'Alexxy' Shvetsov
Petersburg Nuclear Physics Institute, Russia
Department of Molecular and Radiation Biophysics
Gentoo Team Ru
Gentoo Linux Dev
mailto:alexxyum@×××××.com
mailto:alexxy@g.o
mailto:alexxy@×××××××××××××.ru