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From: Sam Ravnborg <sam@ravnborg.org>
To: Sascha Hauer <s.hauer@pengutronix.de>
Cc: Barebox List <barebox@lists.infradead.org>
Subject: Re: [PATCH v1 3/3] at91sam9263ek: add bootstrap support
Date: Thu, 3 Jan 2019 22:00:41 +0100	[thread overview]
Message-ID: <20190103210041.GA20602@ravnborg.org> (raw)
In-Reply-To: <20190103105800.GA27356@ravnborg.org>

Hi Sascha.

Previous mail was written while being disturbed by others - sorry.
 
> > > Fix lowlevel init to get reset vector.
> > > 
> > > Add new MACH_AT91SAM9263EK_BOOTSTRAP config entry
> > > used when building the bootstrap variant.
> > > The new config entry is required as we cannot combine MULTI_IMAGE
> > > with a bootstrap variant.
> > 
> > Why can't that be combined?

> The bootstrap support did not play well with the PBL support.
> And MULTI_IMAGE somehow forced this on me.

So far I have not managed to build a barebox image that would
allow ROMBOOT to load it.
As ROMBOOT is silent about why it fails I have not too much
clue why it fails.

When I compare the disassembled image with and without
PBL support enabled they looks not exactly
the same.
One example is that barebox_image_size is wrong when
I build with PBL / MULTI_IMAGE support enabled.
I need to dig deeper to find out why.
The image size is stored at address 0x14 - but is supposed
to be used only by DataFlast, NOR-flash, so this is likely not
the root-cause. But it looks wrong so one thing to fix.

I will try to chase it a bit more to see if I can get it
to work.


> Note: I also had to disable MMU support to get bootstrap working.
> With MMU enable it halted when __mmu_cache_on() was called in
> mmu-early.c
The above was only partially correct.

If MMU is enabled then I need to comment out the call
to __mmu_cache_on() in mmu_init().
Otherwise barebox just hang right after (or in) the
call to __mmu_cache_on()
(which is a call to v7_mmu_cache_on() )

ROMBOOT will copy barebox to 0x40000 and then remap:
0x40000 => 0x0
0x0 => 0x40000

I guess there is some kind of conflict between the remapping
done by ROMBOOT and the MMU setup / cache setup done by barebox.
So far I am fully satisfied to continue with MMU disabled.

	Sam

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  reply	other threads:[~2019-01-03 21:00 UTC|newest]

Thread overview: 15+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-01-02 20:26 [PATCH v1 0/3] bootstrap support for AT91SAM9263-EK Sam Ravnborg
2019-01-02 20:26 ` [PATCH v1 1/3] arm: at91: fix clock to mci1 for at91sam9263 Sam Ravnborg
2019-01-06 20:39   ` Sam Ravnborg
2019-01-07  7:29   ` Sascha Hauer
2019-01-02 20:26 ` [PATCH v1 2/3] lib: bootstrap: detect SD card before mounting Sam Ravnborg
2019-01-02 23:32   ` Andrey Smirnov
2019-01-03  5:46     ` Sam Ravnborg
2019-01-03 19:53       ` Sam Ravnborg
2019-01-04  7:46         ` Sascha Hauer
2019-01-06 20:39           ` Sam Ravnborg
2019-01-02 20:26 ` [PATCH v1 3/3] at91sam9263ek: add bootstrap support Sam Ravnborg
2019-01-03  8:16   ` Sascha Hauer
2019-01-03 10:58     ` Sam Ravnborg
2019-01-03 21:00       ` Sam Ravnborg [this message]
2019-01-04  7:37         ` Sascha Hauer

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