Re: [MirageOS-devel] Mirage on Xen/ARM status

[Thomas Leonard <talex5@xxxxxxxxx>]

On 5 June 2014 21:29, Anil Madhavapeddy <anil@xxxxxxxxxx> wrote:
> On 4 Jun 2014, at 13:33, Thomas Leonard <talex5@xxxxxxxxx> wrote:
>
>> An update on the Mirage/ARM port:
>>
>> I have mirage-platform upgraded to the new Mini-OS (plus openlibm and
>> no libc). Networking is working again on x86_64 (I can telnet to the
>> mirage-skeleton/network service and send it a message), but not on ARM
>> yet.
>
> Good to have x86_64 back!  It's probably a good idea to CC me and Dave
> on the patchbombs to xen-devel, as I only sample the list these days
> due to mail volume.
>
>> This required some changes to Mini-OS to expose the grant table
>> details and to stop Mini-OS's xenbus from stealing the event
>> notifications. I need this clean this up.
>
> To be clear, this is networking using lwIP on ARM isnt it?  For Mirage,
> the MiniOS Xenbus should be disabled entirely since our own OCaml
> Xenstore will handle everything.

By default, minios's event handler calls do_event on each event, and
loops until they're all handled, so I had to disable that code.

>> OCaml's Random currently tries to open /dev/urandom, which fails.
>> Looks like it falls back to using gettimeofday in that case. It logs a
>> message to the console ("Attempt to open(/dev/urandom)!"), so
>> hopefully we'll remember to fix it eventually.
>
> Is this initialised forcibly anywhere, or only when someone calls
> a Random.self_init()?  We need to deprecate this module in Mirage and
> ensure that we have a randomfront/back model, or risk introducing
> poor entropy.  This hasn't mattered so far, but will be critical when
> we activate the OCaml TLS library that Hannes and David are working on.

The TCP/IP stack seems to want it.

>> Networking doesn't work on ARM as the code wants to use start_info,
>> which doesn't exist. I might try making a fake start_info page on ARM
>> rather than modifying everything else.
>
> Yep, sounds like a good plan to ease x86/ARM transition.

Here are some instructions for testing the current version of
everything (hacks and all!):

To test Mirage on Xen/ARM:

These instructions are for building on a soft-float ARM machine (or
VM), running on the board itself. If you prefer, you can cross-compile
Mini-OS and openlibm and copy the files across (the cross compiler
can be hard-float or soft-float; use DESTDIR=... to stage the files):

  make XEN_TARGET_ARCH=arm32 CROSS_COMPILE=arm-linux-gnueabihf-

However, it doesn't save much time and you still need to build the
OCaml code on the machine itself.


1. Install libminios.a

git clone -b arm-preview https://github.com/talex5/xen.git mini-os
cd mini-os
./configure
cd extras/mini-os

make CONFIG_TEST=n CONFIG_XENBUS=n CONFIG_START_NETWORK=n
CONFIG_BLKFRONT=n CONFIG_NETFRONT=n CONFIG_FBFRONT=n CONFIG_KBDFRONT=n
CONFIG_CONSFRONT=n CONFIG_XC=n -j4 install

3. Get openlibm and install

git clone https://github.com/JuliaLang/openlibm.git
cd openlibm
make install

4. Pin mirage-platform

git clone -b arm-preview https://github.com/talex5/mirage-platform.git
opam pin mirage-xen ./mirage-platform

5. Pin mirage-console

git clone -b arm-preview https://github.com/talex5/mirage-console.git
opam pin mirage-console-xen ./mirage-console

6. Pin mirage

git clone -b arm-preview https://github.com/talex5/mirage.git
opam pin mirage mirage

7. Build mirage-skeleton/console

git clone git://github.com/mirage/mirage-skeleton.git
cd mirage-skeleton/console
opam install mirage
mirage configure --xen
make


The next step is to get networking working on ARM.


-- 
Dr Thomas Leonard        http://0install.net/
GPG: 9242 9807 C985 3C07 44A6  8B9A AE07 8280 59A5 3CC1
GPG: DA98 25AE CAD0 8975 7CDA  BD8E 0713 3F96 CA74 D8BA

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