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Date:      Wed, 11 Nov 1998 01:01:34 -0800
From:      David Greenman <dg@root.com>
To:        Terry Lambert <tlambert@primenet.com>
Cc:        grog@lemis.com, Reinier.Bezuidenhout@KryptoKom.DE, freebsd-hackers@FreeBSD.ORG
Subject:   Re: Malloc in the kernel 
Message-ID:  <199811110901.BAA13927@root.com>
In-Reply-To: Your message of "Wed, 11 Nov 1998 07:21:56 GMT." <199811110721.AAA04416@usr01.primenet.com> 

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>> >> > In general, the kernel is better at deciding what memory it needs
>> >> > when it needs it than a kernel code author.  You either trust
>> >> > the locality of reference model upon which VM systems are based,
>> >> > or you don't.
>> >> 
>> >> Assuming that fits his needs, what's the answer?
>> >
>> >vm_pager_allocate(OBJT_SWAP, 0, OFF_TO_IDX(size), VM_PROT_DEFAULT, 0);
>> 
>>    Bzzt! Wrong!
>> 
>>    ...but you could use kmem_alloc_pageable() (or call vm_map_find() directly)
>> to allocate demand-zero, pageable, kernel memory.
>
>Hmmm....
>
>
>Better fix /sys/kern/sysv_shm.c then, since that's where I cribbed the
>code from...

   sysv_shm.c is a special beast that specifically *avoids* allocating kernel
VM for the objects it manages.

-DG

David Greenman
Co-founder/Principal Architect, The FreeBSD Project

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