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RE: warm boot detection


Most of the integrated processors have a number
registers that are initialized differently depending
on the reset source. On the MPC850, there is a
a Reset Status Register in the IMMR that lists the
reset cause. It cannot differentiate between
hard reset and power. However, the PLPRCR has
a number of bits that are initialized by a power on
sequence but not by a hard reset. We use one of these
(FIOPD) to determine if the reset was the result of
a power on event.

Doug Fraser

> -----Original Message-----
> From: Jonathan Larmour [mailto:jifl@eCosCentric.com]
> Sent: Monday, June 23, 2003 12:05 PM
> To: aarichar@cisco.com
> Cc: Ecos-Discuss
> Subject: Re: [ECOS] warm boot detection
> 
> 
> Aaron Richardson wrote:
> > Is there some way that I can detect if the platform has 
> been cold booted or 
> > warm booted?  It would be nice to avoid initializing 
> several things based on 
> > this.  The SDRAM scrubbing and any memory testing could be skipped.
> 
> Normally people simply rely on the HAL startup type (ROM/RAM etc.) to 
> indicate whether this instance should do the initialization. 
> If you mean a 
> non-eCos program may have done the init on the other hand...
> 
>  >  Also any
> > chips that need to be skipped during a warm boot could be(I 
> have a 21555 pci 
> > bridge that needs to be skipped).
> 
> Surely the best thing is to look at some register in the PCI 
> BIOS to see 
> if it's already been initialized?
> 
> Or since this is an application specific customisation, just 
> add a bit of 
> memory at a common address. Look at how hal_dram_size is 
> treated in the 
> ARM arch HAL for example. Just write a magic number into that 
> address when 
> booted for the first time and use that to test if it's 
> already been booted 
> before.
> 
> Jifl
> -- 
> eCosCentric    http://www.eCosCentric.com/    The eCos and 
> RedBoot experts
> --[ "You can complain because roses have thorns, or you ]--
> --[  can rejoice because thorns have roses." -Lincoln   ]-- 
> Opinions==mine
> 
> 
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