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Re: [RFC] [IP22] parsing PROM variables at startup

To: Dmitri Vorobiev <dmitri.vorobiev@gmail.com>
Subject: Re: [RFC] [IP22] parsing PROM variables at startup
From: Ralf Baechle <ralf@linux-mips.org>
Date: Tue, 13 Oct 2009 22:40:29 +0200
Cc: Linux-MIPS <linux-mips@linux-mips.org>, davem@davemloft.net
In-reply-to: <90edad820910131330t67d6b293o150bef62aec0c5eb@mail.gmail.com>
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References: <90edad820910131055t3cb46d39t87fa568c001634cf@mail.gmail.com> <20091013195822.GA2686@linux-mips.org> <90edad820910131330t67d6b293o150bef62aec0c5eb@mail.gmail.com>
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On Tue, Oct 13, 2009 at 11:30:29PM +0300, Dmitri Vorobiev wrote:

> >> I tried booting a few kernels, ranging from 2.2.1 to the current Linus
> >> Git, on my IP22s using an ecoff image directly, without the help of
> >> arcboot or tip22. It turns out that during many years (at least, since
> >> the times of late 2.4 series) the sizes of ecoff images have been so
> >> big that ARCS was not capable of reading the kernel images. Therefore,
> >> I'd like to claim that it's safe to assume that at least from now on,
> >> nobody is ever going to boot ecoffs on IP22 whatsoever, and arcboot
> >> and tip22 remain the only way to load Linux on an IP22 machine.
> >
> > Only the very oldest IP22 firmware does not support ELF files.  In practice
> > those seem to be very rare - I never encountered one - and Linux
> > distributions are shipping a 2nd stage bootloader, so there never has
> > been much of a need for booting ECOFF, at least not on Indy.
> 
> That is, it's safe to assume that it's either a 32-bit ELF or a 2nd
> stage bootloader that gets loaded by the firmware.

Yes.  The IP22 firmware does not support 64-bit ELF, so 64-bit kernels
have to be converted to 32-bit ELF for booting first.  The vmlinux.32
target does that.

  Ralf

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