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List:       freebsd-hackers
Subject:    Re: solved: pmbr: Boot loader too large
From:       Daniel Braniss <danny () cs ! huji ! ac ! il>
Date:       2013-01-23 9:45:11
Message-ID: E1TxwtL-0004Zi-Vl () kabab ! cs ! huji ! ac ! il
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> > never underestimate the human stupidity (mine in this case) nor of the boot.
> > pmbr will load the whole partition, which was 1M, instead of the size of
> > gptboot :-(
> > 
> > reducing the size of the slice/partition fixed the issue.
> 
> pmbr doesn't have room to be but so smart.  It can't parse a filesystem, so it 
> just loads a raw partition assuming that the partition is the boot loader.  
> The 545k bit has to do with where it is loaded.  The boot loader has to live 
> in the lower 640k, but it starts at 0x7c00 (the address that the BIOS always 
> loads boot loaders).  The 545k limit comes from 640k - 0x7c00.  This is a 
> fundamental limit of the x86 BIOS architecture.  Compared to the 15.5k that 
> UFS leaves for boot2 it is worlds of space.

thanks for the info.
If the error message was clearer might have saved
some time :-)
	Partition size too big
instead of
	Boot loader too large

btw, thanks to grep -r I was to find it came from pmbr.s


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