Date: Tue, 25 Nov 2008 13:00:21 -0700 (MST) From: "M. Warner Losh" <imp@bsdimp.com> To: stas@FreeBSD.org Cc: arm@FreeBSD.org Subject: Re: Code review request: boards on AT91 Message-ID: <20081125.130021.1210474290.imp@bsdimp.com> In-Reply-To: <20081125224528.4395ff7e.stas@FreeBSD.org> References: <20081125222258.8db7b61e.stas@FreeBSD.org> <20081125.123321.-1435626397.imp@bsdimp.com> <20081125224528.4395ff7e.stas@FreeBSD.org>
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In message: <20081125224528.4395ff7e.stas@FreeBSD.org>
Stanislav Sedov <stas@FreeBSD.org> writes:
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: On Tue, 25 Nov 2008 12:33:21 -0700 (MST)
: "M. Warner Losh" <imp@bsdimp.com> mentioned:
:
:
: > We don't universally use it. It is used in the mv code, but not in
: > the at91 code. The at91 boot loader just passes one variable in now,
:
: Just a matter of time:-) As I said we have the patch almost ready,
: and it works for us with u-boot. I'll commit it shortly.
So long as it is optional. The KB9202 boards that I have don't have
room for uboot or redboot. You have 16kb of space, which boot2 fits
nicely into right now (clocking in at about 9.5k).
: > but there's a fair number of different boot loaders today for
: > FreeBSD/arm. While it would be nice to mandate all the world use
: > uboot + /boot/loader, that's not likely going to happen. There's too
: > many boards out there that have redboot or some custom boot loader
: > that will be hard to replace...
:
: In that cases loader(8) could be used.
Not always. That's the point that I keep coming back to. There's no
easy way to make loader read things from disks, over the network, etc
in the embedded space. Right now for some uboot based systems, this
can be done, but for redboot systems, you are basically out of luck.
There's no way that loader(8) can load additional sections without a
lot of board specific code.
: > I guess what I'm trying to say is that the current mechanisms we're
: > using are all over the map, and we need to clean it up so that it is
: > easy to swap different types of boot loaders in.
:
: Agree. At least, for some architectures the kernel config option could
: be added to switch between bootloader support. It'd be hard to make
: this in the platform independent code...
Yes. There's some things that can be common, but there will always be
machine dependent code. uboot, redboot and cfe all are multiplatform.
Warner
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