GRUB and OLPC

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GRUB and OLPC

Vladimir 'φ-coder/phcoder' Serbinenko
Hello, all. GRUB has supported OLPC for quite some time but I don't know
if there are any remaining users. Given how small the intersection
between geeks and XO-1 owners nowadays is, continuing support is
problematic. Among other things it's likely to degrade over time unless
at least minimum maintainance is done. AFAIK none of the active GRUB
maintainers even possesses one. The current regular testing is limited
to checking whether it builds. The underlying OLPC ieee1275 firmware
implementation OFW supposedly supports also qemu and coreboot. While
it's still somewhat functional in qemu, it lacks important drivers for
modern system when booted with coreboot, most notably AHCI. Some basic
automated testing can be performed with OFW on qemu. They currently
aren't, another gap needed to fill.
Half of the drivers for OLPC aren't included in this OFW-qemu, each of
them with specific interface. As a matter of fact we have some
workarounds enabled for real OLPC which are not needed in qemu but
without them GRUB would hang on real machine. I don't know if they still
work. So tests on qemu are better than nothing but give very small
guarantee. Also OLPC is at intersection of generic i386
XT-almost-compatible and OFW. Whether ieee1275 or i386 functions work
better can be inferred from testing on real hardware but failing that
none is used and corresponding functionality is just disabled. Because
of all these reasons i386-ieee1275 lags behind and missing features
often require special case-checking in other parts. E.g. write-back to
nand is probably trivial to implement but can't be so without testing.
Supporting jffs2 on nand without testing isn't realistic either.
Because of all these reasons it may be time to either find solutions to
at least some of problems (mainly lack of testing) or to retire the port
altogether.

P.S: attitude of OFW devs of rejecting even an idea of GRUB for OLPC
like I've just experienced on IRC isn't helpful.


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Re: GRUB and OLPC

James Cameron-2
On Mon, Apr 08, 2013 at 12:45:25AM +0200, Vladimir '??-coder/phcoder' Serbinenko wrote:
> P.S: attitude of OFW devs of rejecting even an idea of GRUB for OLPC
> like I've just experienced on IRC isn't helpful.

I do apologise if my seeking for information appeared to be rejecting
the idea of GRUB for OLPC XO-1.  I really had no idea what you were
talking about, and you had to teach me first.  Since I am very
familiar with how OFW boots Linux, and not at all familiar how GRUB
boots FreeBSD, I am obviously biased toward OFW doing the task.

I look forward to hearing from users of GRUB booting on XO-1.  It
sounds like an interesting challenge.

--> phcoder (~[hidden email]) has joined #olpc
<phcoder> Hello, all. Is anybody uses / is interested / finds interesting / ... GRUB2 OLPC support?
<-- PhoenixSTF has quit (Ping timeout: 276 seconds)
<Quozl> grub is for PC BIOS, but OLPC XO has non-PC BIOS, therefore grub seems irrelevant.  what feature of grub are you looking for?
<phcoder> Quozl: wrong. Platforms currently supported by GRUB:
<phcoder> GRUB_PLATFORMS = [ "emu", "i386_pc", "i386_efi", "i386_qemu", "i386_coreboot",
<phcoder>                    "i386_multiboot", "i386_ieee1275", "x86_64_efi",
<phcoder>                    "mips_loongson", "sparc64_ieee1275",
<phcoder>                    "powerpc_ieee1275", "mips_arc", "ia64_efi",
<phcoder>                    "mips_qemu_mips" ]
<phcoder> 2 more in merge queue, yet one more in developpement
<Quozl> What would be the point?
<Quozl> (i'm willing to be convinced there is a valid purpose, but for the moment i can't see one).
<phcoder> I think you don't see the current situation: OLPC is supported by GRUB2. The question is whether this support should be dropped as OLPC dies out and distances itself from geeks.
<Quozl> I can't see OLPC in the GRUB_PLATFORMS, can you?
<phcoder> i386-ieee1275 is OLPC
<Quozl> Neato.  How could I have known that?
<phcoder> ieee1275 is openfirmware
<Quozl> I couldn't speak for the users of said support.  I've never used it, since the Open Firmware we have includes the necessary code to load kernel and ramdisk of any number of Linux instances.
<Quozl> Why was i386-ieee1275 added?
<phcoder> But not e.g. FreeBSD
<phcoder> And it's easier to adapt existing distro by simply changing installed GRUB flavour that dancing with OFW.
<Quozl> I'm sure Open Firmware could boot FreeBSD if somebody tried hard enough.
--> PhoenixSTF (~rudi@83.240.154.11) has joined #olpc
<Quozl> So the choice is between dancing with GRUB or dancing with Open Firmware?  I'm biased, I'd always dance with Open Firmware.  So you should not ask me my opinion, as I have no relevant experience.
<Quozl> Seems like a waste of time to have Open Firmware transfer control to GRUB only to have GRUB ask Open Firmware to read certain sectors and transfer control to something else.
<Quozl> How quickly does this combination boot?
<Quozl> No ARM support?
<phcoder> Quozl: let me explain: all OLPC-grub devs have gone inactive, that's why the question of retiring the port is on the table in the first place. None of devs even has OLPC. The tests on i386-ieee1275 are performed at best in qemu but your OFW flavour seems to work well only with OLPC, despite claiming to work on qemu and coreboot as well (I tested both)
<Quozl> Show me the tests?
<phcoder> On coreboot it plainly doesn't see the disks (no AHCI support). Couldn't go any further from there.
<phcoder> On qemu it overwrites 1M-1.5M range despite it being marked as usable
<cjb> phcoder: someone on [hidden email] might be interested in helping
<phcoder> perhaps sth more. I workarounded the ofw-qemu bugs to make our automated tests run.
<cjb> it seems clear that Quozl isn't :-)
<Quozl> Are you sure this isn't breakage caused by qemu?  ;-)
<Quozl> I've not used coreboot.  I'm just grabbing grub2 sources to find these tests.
<phcoder> cjb: I'm composing a mail now to grub-devel, [hidden email] and [hidden email] to see if there is a way to reasonably keep it around
<cjb> sounds good, thanks
<phcoder> Quozl: on ofw-i386 they are not automated: I gave up when searching for a way to boot grub.elf directly rather than going to prompt
<Quozl> Automate by creating a directory boot and a file olpc.fth in it that names grub.elf in place of the kernel?
<phcoder> Shipping price to Europe doubles the price of OLPC XO-1
<phcoder> I don't speak forth
<Quozl> You can learn.
<phcoder> Quozl: I'm not interested in it.
<Quozl> Okay.

--
James Cameron
http://quozl.linux.org.au/
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Re: GRUB and OLPC

Mitch Bradley-2
In reply to this post by Vladimir 'φ-coder/phcoder' Serbinenko
OLPC stopped making x86 machines some time ago.  XO-1 machines have
reached or exceeded their design lifetime.  I expect that, if there are
any active users of GRUB on OLPC machines, upgrading to new versions of
GRUB-booted OSs is becoming less and less attractive due to resource
constraints and hardware aging.

OLPC was targeted toward a very specific audience, and the overwhelming
number of active users is within that target audience.  In the early
days there was a lot of interest from developers of other OSs, but as
far as I can tell, that waned years ago as other platforms started to
capture peoples interest.

That being the case, I don't see any compelling reason to continue
maintaining the support.  Existing users could continue to use their
working builds.  It is hard to imagine that there are many (if any)
people who have a real need to install a fresh new version.

I would say that it is time to move on.

On 4/7/2013 12:45 PM, Vladimir 'φ-coder/phcoder' Serbinenko wrote:

> Hello, all. GRUB has supported OLPC for quite some time but I don't know
> if there are any remaining users. Given how small the intersection
> between geeks and XO-1 owners nowadays is, continuing support is
> problematic. Among other things it's likely to degrade over time unless
> at least minimum maintainance is done. AFAIK none of the active GRUB
> maintainers even possesses one. The current regular testing is limited
> to checking whether it builds. The underlying OLPC ieee1275 firmware
> implementation OFW supposedly supports also qemu and coreboot. While
> it's still somewhat functional in qemu, it lacks important drivers for
> modern system when booted with coreboot, most notably AHCI. Some basic
> automated testing can be performed with OFW on qemu. They currently
> aren't, another gap needed to fill.
> Half of the drivers for OLPC aren't included in this OFW-qemu, each of
> them with specific interface. As a matter of fact we have some
> workarounds enabled for real OLPC which are not needed in qemu but
> without them GRUB would hang on real machine. I don't know if they still
> work. So tests on qemu are better than nothing but give very small
> guarantee. Also OLPC is at intersection of generic i386
> XT-almost-compatible and OFW. Whether ieee1275 or i386 functions work
> better can be inferred from testing on real hardware but failing that
> none is used and corresponding functionality is just disabled. Because
> of all these reasons i386-ieee1275 lags behind and missing features
> often require special case-checking in other parts. E.g. write-back to
> nand is probably trivial to implement but can't be so without testing.
> Supporting jffs2 on nand without testing isn't realistic either.
> Because of all these reasons it may be time to either find solutions to
> at least some of problems (mainly lack of testing) or to retire the port
> altogether.
>
> P.S: attitude of OFW devs of rejecting even an idea of GRUB for OLPC
> like I've just experienced on IRC isn't helpful.
>
>
>
> _______________________________________________
> Testing mailing list
> [hidden email]
> http://lists.laptop.org/listinfo/testing
>
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