[Xen-users] Fw: Fw: booting

[IAN DELANEY <della5@xxxxxxxxxxxx>]

Begin forwarded message:

Date: Wed, 5 Feb 2014 11:35:50 +0800
From: IAN DELANEY <della5@xxxxxxxxxxxx>
To: Ian Campbell <Ian.Campbell@xxxxxxxxxx>
Subject: Re: [Xen-users] Fw: booting


seems it needed manual CC'ing

On Tue, 4 Feb 2014 15:16:12 +0000
Ian Campbell <Ian.Campbell@xxxxxxxxxx> wrote:

> On Tue, 2014-02-04 at 12:50 +0800, IAN DELANEY wrote:
> 

> Lastly, please drop the aggressive tone, I appreciate that you have
> found this frustrating, but it is not going to encourage people to try
> and help you.
> 

Let's bring this to the top where it is more apt.  Firstly thx for
the informative response.  We have exchanged in the past couple of
years, some emails in the xen-devel list, all to do with the build of
xen in amd64 x86.   At the risk of being argumentative, the tone or
intent isn't so much aggressive, rather 'telling it it like it is' in
this case from my perspective attempting to boot xen in one arm board.
I'm Australian which we don't have in common I'm pretty sure.  It's a
'cultural cringe' that you experience here I believe.   We down under,
at least the men, call a spade a bloody shovel as par for the course.

"This underlines the problem with the wki for
Xen_ARMv7_with_Virtualization_Extensions. It's both faulty and as clear
as proverbial mud" is such an instance. While it's bold,  I consider it
falls short of aggressive since I fundamentally object to aggressive.
"Get your act together and write something that makes sense and a
reader can actually follow" to me qualifies as aggressive.  It has the
'put down', it's antagonistic and basically insults, all of which, in my
judgement, I refrained from.  Suffice to say, I used what in a
literature sense is use of 'hyperbole' so as to illustrate a point.
It's a communication 'strategy'.  Those points I made were indeed driven
home.  However, that does indeed run the 'risk' of being read or
interpreted as brazen and hostile, communication by its nature being a
highly abstract and inexact science.  

So let's balance this with, from my prior dealings with you, I hold you
and your advice in good regard, and I extend my regret if my
description resulted in any form of offence on your part.

Now for the subject at hand;

 
> I'm afraid that Xen on ARM is not yet aimed at the total newbie on
> ARM.
> 

Well, pity that.  My aim here is to attempt to do what has been made
doable according to what I understand.   The release of xen-4.3 over 6
months ago declared xen arm capable and equipped.  At my end here, I
submitted a request many months ago for gentoo's arm arch team to
keyword xen to ~arm.  Two devs tried it and it failed to build.  So
they then did nothing about it.  Minor arch teams typically have a tiny
membership and are persistently reported as being understaffed and over
worked. Anyway I ended up acquiring a cubieboard2 for the purpose of
doing it myself because the others simply weren't delivering.  To date,
I have got xen to build by doing the required tweaks that they found
too hard mostly due to xen being a demanding build in its own right.  I
always knew the booting into a xen equipped kernel plus the hypervisor
would be a huge ask, and indeed it is. I love a challenge!

> I appreciate that things are not as clear as they might be, I'm sorry
> but at this stage I think it is not unreasonable to expect that people
> try Xen on ARM are already somewhat familiar with Linux on ARM, which
> means u-boot and some of the terms used here.  
> 

> I have no idea what you've done here but Linux 3.4 just won't work
> with Xen on ARM.
> 

1.  u-boot I gather is very low level and appears to require a
significant climb of the learning curve to even begin to use it. 

2.  The 3.4-75 kernel is the one utilised by sunxi in the link in the
wiki page(s).  The booting into the uImage of 3.4-75 is merely the
u-boot booting process gone awry.  The zImage of the 3.13 was there
and it was  seemingly missed.  The point is that the boot.xen ->
boot.scr I edited from the wiki / prepared were ineffective.  But let's
move past that one state, move on.

3.  The gentoo dev of the minor arch arm team has used only the
specially equipped sunxi 3.4-75 kernel to boot the CB2.  Beyond that,
he appears too occupied to take the next step and get it to boot off the
xen equipped capable and adequately arm equipped sunxi 3.13-rc4 kernel. 
Although he does provide the odd tip, he basically cut me loose by
tapping out somethink like "that (booting xen) is way out of what my
territory, you're on your own in irc.
Pity that 

4.  The technical point that appears to be tripping me appears to be
the nominating of the load address of the kernel.  The 3.4 kernel that
I boot uses fatload (the boot partition is vfat), a uImage and a
bootm. 

5. The boot.cmd I have to boot goes from a 4 line script to a boot.xen
that switches everything.  uImage is out, bootm is out. In, we have
zImage (never heard of it), bootz (ditto) and a whole new scripting set
(u-boot boot.cmd/boot.xen)

> I'm sorry
> but at this stage I think it is not unreasonable to expect that people
> try Xen on ARM are already somewhat familiar with Linux on ARM,

I have a better knowledge of arm than a fortnight ago, however, I'm
sorry but all of the above make for a horrendously steep learning
curve.  On the plus side, your tips provided already have already made
some progress towards reducing its incline. 
   
> > Start from the multi_v7_defconfig multiplatform kernel: 
> > 
> > make sun7i_dom0_defconfig
> > 
> > is NOT.  Apparently that kernel is no longer being linked and the
> > current kernel 3.13-rc4 simply does NOT even have the
> > sun7i_dom0_defconfig.
> 
> Sorry, my fault, This was something added to the random github tree
> which used to be pointed to by the guy who wrote the original
> instructions. The right advice is to start from "multi_v7_defconfig".
> 

done

> Actually. It seems I originally managed to change the text but not the
> example.
> 
> I've fixed that now
> 

good, thx

> > "This assumes that the kernel is <4MB, "
> > 
> > leaves me in the lurch because the zImage comes up over 4 mb. and I
> > am not versed in hex maths so as to convert all these addresses,
> > which leaves me vulnerable to making wrong data.
> 
> gnome-calculator speaks hex, as do many other tools.
> 

I'll find one I think, though I don't use gnome

> I'm afraid this is sort of normal for ARM/u-boot systems.
> 

well, part of the learning curve.

> > 
> > "console=hvc0 ro root=/dev/sda1 "
> > 
> > does this pertain to a usb boot?  Mine is actually from an SDHC
> > card, once again making for uncertainty.
> 
> It can be whatever you would use to boot natively on this platform. I
> suspect that means /dev/mmcblkN but I haven't been booting from that
> so I don't know.
> 

Yes; the (1st.) line for the boot.cmd that I have to boot the sunxi 3.4
kernel is " setenv bootargs console=ttyS0,115200 root=/dev/mmcblk0p2
rootwait panic=10 ${extra}"

> > setenv bootargs "console=dtuart dtuart=/soc@01c00000/serial@01c28000
> > dom0_mem=128M"
> > 
> > 
> > What happened to root=.... ?
> 
> That is the hypervisor command line, the root= is a kernel parameter.
> 

ok helpful hint there thx

> >  Parameters for the domain 0 kernel are passed using the
> >  xen,dom0-bootargs
> 
> I don't see any reference to dom0-bootargs on the allwinner page.
> 
> > I initially booted into the CB2 via the 3.4-75 kernel from sunxi
> > with a boot.cmd provided by the arm arch dev @ gentoo. He knows
> > nothing about xen and doesn't even understand what a dom0 is.
> > Currently, despite using a boot.xen amd mkimage a boot.scr from the
> > boot.xen, the CB2 boots into the WRONG kernel.
> 
> > This underlines the problem with the wki for
> > Xen_ARMv7_with_Virtualization_Extensions. It's both faulty and as
> > clear as proverbial mud.  
> 
> > The use of the u-boot is totally new to me having become accustomed
> > to grub.  The instructs for such a challenging and technically
> > intricate process of booting a dom0 in an arm board need be made
> > crystal clear, and it isn't.  I'm circumspect about gaining clear
> > answers from this source and therefore about being able to get the
> > CB2 to boot into dom0.  If a xen maintainer @ gentoo can't follow
> > this literature, what chance a user?
> 
> This stuff isn't even released yet. Nobody has said it is ready for
> end users yet -- it is ready for interested devs to use.
> 

Well, I'm a dev and I'm interested.  From what you say though I just
get the impression that my attempts might be a touch premature.  I'm
reluctant to capitulate though.  I can see it's doable and I'm just
tryin' to do it.   In summary; xen is a monster package, building and
equipping kernels is a heavy weight task, the arm (or any) arch is a
broad and technically challenging field to take on, ditto u-boot.  And
you can do them all.   Thumbs up.

> Anyway, we are trying to make this easier but it is clearly not ready
> yet.

Yes I can see you are, and you're making progress for sure. Thumbs up.

Appreciation and thx for your input, fellow Ian.



-- 
kind regards

Ian Delaney


-- 
kind regards

Ian Delaney

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