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Re: Execute-in-Place (XIP)

To: Chris Boot <>
Subject: Re: Execute-in-Place (XIP)
From: David Daney <>
Date: Fri, 28 Oct 2005 16:08:08 -0700
In-reply-to: <>
Original-recipient: rfc822;
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Chris Boot wrote:

Now, who knows how much initialisation a bootloader is expected to perform? Does the vrboot loader do the necessary operations, in which case I can just work on that instead of writing my own?

It depends.

Depending on the hardware:

Initialize clocks (things like PLL divisors and such).

Initialize serial port so it can report on its progress.

Initialize memory controller (so that RAM functions).

(optionally) copy bootmonitor to ram so that it can run out of cached memory.

(optionally) copy kernel image to ram (possibley uncompressing it) and transfersing control to the kernel.

If you are doing XIP, the last two steps are probably skipped.

I have no idea what the vrboot loader does, but that is what the Xilleon boot loaders do.

David Daney

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