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Date: Sat, 18 Aug 2007 08:23:33 +0200
From: Sam Ravnborg <sam@ravnborg.org>
To: Robin Getz <rgetz@blackfin.uclinux.org>
Cc: linux-kernel@vger.kernel.org, Gerd Hoffmann <kraxel@redhat.com>,
       Alan Cox <alan@lxorguk.ukuu.org.uk>, Bryan Wu <bryan.wu@analog.com>,
       Sonic Zhang <sonic.adi@gmail.com>,
       Mike Frysinger <vapier.adi@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       "H. Peter Anvin" <hpa@zytor.com>
Subject: Re: [draft] Blackfin Early Printk implmentation
Message-ID: <20070818062333.GA26416@uranus.ravnborg.org>
References: <200708152234.06734.rgetz@blackfin.uclinux.org> <200708171336.40159.rgetz@blackfin.uclinux.org> <20070817175911.GA22046@uranus.ravnborg.org> <200708171607.32849.rgetz@blackfin.uclinux.org>
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> > What was preventing you from just using the x86_64 code here?
> 
> Some was borrowed - but not much. since we don't support vga, or 16550 UARTs
> (Blackfin has it's own on-chip UART), I don't think this would work. 
> 
> Maybe I'm missing something - but I don't think so. Every one who implements
> implements direct IO to the hardware (except me, since I put it into the driver
> file, and force Sonic - the serial driver developer - to maintain it forever).
> 
> Most of the other early printks talks directly to the hardware.
I only looked at your version and it looked general thats why I brought
up the code sharing idea - which I agree is not possible.

> > Thinking that all should do the same so maybe alpha ought to change...
> 
> When I looked at all the printk implementations, I thought they were all
> kind of hokey, and not very common - but what do you want for a debug interface
> that lasts less than 5 seconds?
> 
> ./arch/x86_64/kernel/early_printk.c
> ./arch/blackfin/kernel/early_printk.c
> ./arch/sh64/kernel/early_printk.c
> ./arch/sh/kernel/early_printk.c
> ./arch/i386/kernel/early_printk.c
> ./arch/mips/kernel/early_printk.c
> 
> I didn't see an alpha implementation - where is it done?
Alpha uses the imlementation in lib/*print.c somehow.
And I think the right choice would be to implement
a private version of early_printk for alpha like the
other architectures do.

Thanks for the split-up. I could follow the changes now.

	Sam