Date: Tue, 17 May 2011 11:29:39 +0200 From: rank1seeker@gmail.com To: freebsd-hackers@freebsd.org Subject: Re: MD ROOT and image size limitation (makes kernel panic) Message-ID: <20110517.092939.312.1@DEV> In-Reply-To: <BANLkTimQV%2B19g=9TbHCNq1VbDUFoWVaB4Q@mail.gmail.com> References: <20110516.183617.687.1@DEV> <BANLkTimQV%2B19g=9TbHCNq1VbDUFoWVaB4Q@mail.gmail.com>
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> Hi,=0D=0A> =0D=0A> On Mon, May 16, 2011 at 11:36 AM, = <rank1seeker@gmail.com> wrote:=0D=0A> > I have a 4 GB or ram, so why = kernel panic with my MD ROOT, if larger then=0D=0A> > ~40 MB?=0D=0A> > = I've tried to split up root in 20MB image and usr in 160 MB=0D=0A> > Via = loader.conf root becomes md0 and usr md1 and panic occurs even = when=0D=0A> > they are split=0D=0A> >=0D=0A> > I had to get rid of md1, = to be able to boot with md0 as a root.=0D=0A> >=0D=0A> > What exactly = imposes limitation, inside kernel's code to SIZE of an image?=0D=0A> > My = hardware definatelly isn't ...=0D=0A> >=0D=0A> > Is this different on = amd64?=0D=0A> > I've tested this, only with i386.=0D=0A> >=0D=0A> =0D=0A> = We hit this problem at work and the solution was to increase NKPT.=0D=0A> = =0D=0A> If you are using -current then NKPT is already a kernel config = option.=0D=0A> With 8.x you will need to modify = <machine/pmap.h>.=0D=0A=0D=0A=0D=0AWell ..., it looks like my 8.2 RELEASE = src, has it, but ONLY for i386=0D=0A=0D=0A=0D=0A# less = /usr/src/sys/i386/conf/NOTES=0D=0A=0D=0A--=0D=0A#=0D=0A# Number of = initial kernel page table pages used for early bootstrap.=0D=0A# This = number should include enough pages to map the kernel, any=0D=0A# modules = or other data loaded with the kernel by the loader, and data=0D=0A# = structures allocated before the VM system is initialized such as = the=0D=0A# vm_page_t array. Each page table page maps 4MB (2MB with = PAE).=0D=0A#=0D=0Aoptions NKPT=3D31=0D=0A--=0D=0A=0D=0ASo, that = would be 124 MB for kernel and it's modules or other data loaded with the = kernel by the loader (i.e; md image)=0D=0AIn those nums, md image has = only about ~45 MB for itself.=0D=0A=0D=0AKernel itself and it's ..., = needs ~80 MB=0D=0A=0D=0A=0D=0AI'll build a custom kernel, for "lifting" = md image ...=0D=0A=0D=0A=0D=0A=0D=0ADomagoj Smol=E8i=E6=0D=0A=0D=0A
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