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, > > On Mon, May 16, 2011 at 11:36 AM, <rank1seeker@gmail.com> wrote: > > I have a 4 GB or ram, so why kernel panic with my MD ROOT, if larger then > > ~40 MB? > > I've tried to split up root in 20MB image and usr in 160 MB > > Via loader.conf root becomes md0 and usr md1 and panic occurs even when > > they are split > > > > I had to get rid of md1, to be able to boot with md0 as a root. > > > > What exactly imposes limitation, inside kernel's code to SIZE of an image? > > My hardware definatelly isn't ... > > > > Is this different on amd64? > > I've tested this, only with i386. > > > > We hit this problem at work and the solution was to increase NKPT. > > If you are using -current then NKPT is already a kernel config option. > With 8.x you will need to modify <machine/pmap.h>. Well ..., it looks like my 8.2 RELEASE src, has it, but ONLY for i386 # less /usr/src/sys/i386/conf/NOTES -- # # Number of initial kernel page table pages used for early bootstrap. # This number should include enough pages to map the kernel, any # modules or other data loaded with the kernel by the loader, and data # structures allocated before the VM system is initialized such as the # vm_page_t array. Each page table page maps 4MB (2MB with PAE). # options NKPT=31 -- So, 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) In those nums, md image has only about ~45 MB for itself. Kernel itself and it's ..., needs ~80 MB I'll build a custom kernel, for "lifting" md image ... Domagoj Smolčić
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