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Date:      Fri, 12 May 2000 16:04:26 -0700
From:      Peter Wemm <peter@netplex.com.au>
To:        Boris Popov <bp@butya.kz>
Cc:        John Baldwin <jhb@FreeBSD.org>, "Daniel C. Sobral" <dcs@newsguy.com>, freebsd-alpha@FreeBSD.org
Subject:   Re: Loader fixed 
Message-ID:  <20000512230426.89F491CE1@overcee.netplex.com.au>
In-Reply-To: Message from Boris Popov <bp@butya.kz>  of "Fri, 12 May 2000 22:49:20 %2B0700." <Pine.BSF.4.10.10005122227390.65582-100000@lion.butya.kz> 

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Boris Popov wrote:
> On Fri, 12 May 2000, John Baldwin wrote:
> 
> > Here's a broken one:
> > 
> > -r-xr-xr-x  1 root  wheel  186648 May 11 11:48 /boot/loader.old
> > 
> > If we do a little hex work:
> > 
> > > printf "%x %x" 182680 186648
> > 2c998 2d918
> 
> 	I have zero knowledge about Alpha architecture and may be
> completely wrong, but:
> 
> 	Loader load address defined as:
> 
> SECONDARY_LOAD_ADDRESS= 0x2000c000      # "Region 1 start" + 48k
> 
> 	As I can see from sources, at the boot moment here is only one
> page of 256K dedicated to loader, so:
> 
> 	256*1024 - 0xc000 - 0x2d918 = 26344
> 
> 	A loader binary doesn't contain BSS segment which consists of
> stack (8KB) and uninitialized data.
> 
> 	It is quite possible, that together with BSS data, total loader size
> exceeds 256k limit (and/or overlaps with heap which may explain
> mysterious zfree() error).

For what it's worth, we have to load /boot/loader into a 256k-48k (208k)
space. We have presently got 13.5K of free space for loader to squeeze
into.  We have ~8.5K of free space for boot1.  We might have to move the
expand_heap() code from loader into boot1 to get more breathing room for
when loader gets longer next time.  expand_heap() might fit into the
8.5k, *but* it would require everybody to reinstall their bootblocks or
loader will no longer work if it's expecting the bootblocks to do the dirty
work for it.

Cheers,
-Peter



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