Date: Tue, 1 Jun 2010 10:20:01 -0400 From: John Baldwin <jhb@freebsd.org> To: Jeremy Chadwick <freebsd@jdc.parodius.com> Cc: Garrett Cooper <yanefbsd@gmail.com>, freebsd-stable@freebsd.org, Clifton Royston <cliftonr@lava.net> Subject: Re: Locking a file backed mdconfig into memory Message-ID: <201006011020.01318.jhb@freebsd.org> In-Reply-To: <20100531184525.GA89545@icarus.home.lan> References: <201005272348.o4RNmgWh014243@hugeraid.jetcafe.org> <201005311825.o4VIPp5F051573@hugeraid.jetcafe.org> <20100531184525.GA89545@icarus.home.lan>
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On Monday 31 May 2010 2:45:25 pm Jeremy Chadwick wrote: > On Mon, May 31, 2010 at 11:25:51AM -0700, Dave Hayes wrote: > > Jeremy Chadwick <freebsd@jdc.parodius.com> writes: > > > Is the mfsroot file compressed (.gz extension)? Reason I ask is that > > > the OP states he's using RELENG_7... > > > > Yes it is compressed. > > > > > http://jdc.parodius.com/freebsd/pxeboot_serial_install_7.html#step7 > > > > Thanks much for this. I did a simple test, I rebuilt a DVD that wasn't > > booting to use a lower level of compression (gzip -9 to gzip -6) on > > mfsroot without changing anything else. This caused it to boot normally. > > > > I'm not sure it's conclusive evidence, but it certainly looks like a > > weak datapoint supporting this kernel bug being the source of my > > problem. > > > > Is this problem fixed in 8.0 or by a patch? > > With regards to said bug, gzip compression seems to work fine on > RELENG_8, at least in my experiences: > > http://jdc.parodius.com/freebsd/pxeboot_serial_install_8.html > > I'm not sure the level of compression is what triggers the bug though; > I haven't tested all levels (1 through 9). > > CC'ing jhb@ since he last updated PR kern/120127 (which I would say is > still a problem on RELENG_7 :-) ). John, are you aware of any gzip > decompression / mfsroot changes which might explain the problem on > RELENG_7? I haven't done a "thorough" series of tests, but on my > testbed boxes RELENG_8 works fine with a gzip'd mfsroot. Ok, if you are using a stock mfsroot from a release build, that should work fine. If you have built a custom mfsroot that is larger, then you may need to increase NKPT on i386. In very recent 7 and later you can do this by setting it to a new value in your kernel config. In older versions you can do this by manually adding a #define to set a new value of NKPT in opt_global.h or hacking on the source directly. -- John Baldwin
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