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Date:      Mon, 9 Oct 2000 09:52:54 +0100
From:      Bob Bishop <rb@gid.co.uk>
To:        Peter Wemm <peter@netplex.com.au>
Cc:        Mike Smith <msmith@FreeBSD.ORG>, Mitsuru IWASAKI <iwasaki@jp.FreeBSD.org>, keichii@peorth.iteration.net, current@FreeBSD.ORG
Subject:   Re: Recent kernels won't boot
Message-ID:  <l0313030ab60736d8694e@[194.32.164.2]>
In-Reply-To: <200010090804.e99841G14893@netplex.com.au>
References:  <200010090610.e9969xh03937@mass.osd.bsdi.com>

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Hi,

At 01:04 -0700 9/10/00, Peter Wemm wrote:
>Mike Smith wrote:
>> > > That was it. Is the 4MB kernel size limit documented anywhere?
>> >
>> > I don't know :-)   I luckily noticed this by a lot of trials.
>>
>> I'm not aware of any 4MB limit on kernel size (and I ought to be if there
>> is one 8).  Can you run the details past me?  (I've regularly booted much
>> larger kernels in the past...)
>
>Uhh, are you sure?  Ignore the size of the file, what does 'size(1)' say
>about these large kernels?  Does text+data+bss excede 4MB?  I have a
>nagging suspicion that we only set up 4MB of page tables during the early
>part of the bootstrap process in locore.s.  (forgive me for not looking,
>I have a most evil headache and locore.s is no way to improve it :-).
>Thinking about it some more, there may be a 3MB limit as we load above
>1MB.  I recall some heavy magic with the SMP bootstrap where we only use one
>PTD slot for 0-4MB in early boot....

Example:

% size kernel*/kernel
   text    data     bss     dec     hex filename
3302182  206816 2265368 5774366  581c1e kernel.old/kernel
2947194  207168  168152 3322514  32b292 kernel/kernel

Same kernel config except that top one includes KTR options and won't boot,
bottom one has no KTR and boots OK. I've been running with SMP_DEBUG, KTR
and the rest for a while, this trouble started a few days ago.


--
Bob Bishop              (0118) 977 4017  international code +44 118
rb@gid.co.uk        fax (0118) 989 4254




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