From mboxrd@z Thu Jan  1 00:00:00 1970
From: Andrew Lunn <andrew.lunn@ascom.ch>
To: Grant Edwards <grante@visi.com>
Cc: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] RedBoot porting
Date: Mon, 08 Jan 2001 00:29:00 -0000
Message-id: <20010108092928.I10158@biferten.ma.tech.ascom.ch>
References: <20010105115220.A2486@visi.com>
X-SW-Source: 2001-01/msg00062.html

> If I do not want RedBoot to provide any services to user
> applications, do I still need to implement virtual vector
> support in my HAL?  [Having application code depend on services
> available in the boot loader is way too high-risk, since there
> isn't going to be any way to upgrade the boot loader in the
> field.]

Even if you could try to upgrade the boot loader in the field, its
hard to do. In my case the boot loader is in FLASH. My code has a TFTP
server running that allows me to download new images into the
FLASH. The problem with redboot is that you have no control when it
tries to jump into the ROM. A typical sinario is that i erase a block
and start writing bytes to it. The app then decides to jump into
Redboot, typical for ^C support reasons. The FLASH is currently in
write mode so the first instruction read in ROM returns the status
code of the current write, which the CPU tries to execute and its RIP,
you dead.

What would be nice is being able to tell the app, don't jump into ROM
for a while, i need exclusive access to the FLASH. 

        Andrew