Date: Sun, 12 Feb 2006 00:37:04 -0500 From: Sergey Babkin <babkin@verizon.net> To: Jacques Fourie <jf@trispen.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Pre-loaded mfsroot size and FreeBSD 4.9 with 4G RAM Message-ID: <43EEC980.32C2FA40@verizon.net> References: <20060208164141.GA21718@trispen.com> <20060208185836.GA55307@xor.obsecurity.org> <20060209092139.GB21718@trispen.com> <op.s4rjho0bwikogb@jf64x2.trispen.com>
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Jacques Fourie wrote: > > I have installed 6.0-RELEASE and the behaviour is still the same. If I try > to pre-load an md_image of 64M with 4G of RAM installed, the kernel panics > early in the boot cycle. Here is the panic on 6.0-RELEASE: > > 131072K of memory above 4GB ignored This is a kind of stupid question but is there any chance that the 64MB image overlaps with the PCI address hole? To elaborate: with 4GB memory installed there would be no address range to access the memory-mapped 32-bit PCI cards. So the motherboard circuitry relocates some amount of memory (the 128MB shown above) from some lower address to above 4GB and frees this address space below 4GB for mapping of the PCI cards. So the interesting question is: what is the address of this PCI hole and what is the loading address of the FreeBSD md_image? If they overlap then naturally a part of the image would go into nowhere and cause a panic. On my machine this PCI hole can be disabled in BIOS (I think so, there is also some kind of configuration in BIOS but I did not pay much attention to it as I don't have 4GB). -SB
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