Date: Sun, 15 Sep 2002 21:38:35 +0100 From: Dominic Marks <dominic_marks@btinternet.com> To: Jamie Heckford <jamie@jamiesdomain.org.uk> Cc: freebsd-hackers@freebsd.org Subject: Re: Kernel - Modules and Compiled in Message-ID: <20020915203835.GA3497@gallium> In-Reply-To: <001001c25d36$a3672be0$83bf83d5@BONG> References: <001001c25d36$a3672be0$83bf83d5@BONG>
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On Sun, Sep 15, 2002 at 09:07:56PM -0700, Jamie Heckford wrote: > Hi, > > I've noticed by having to admin a few linux boxes in my time that the majority of the kernel > drivers are loaded via modules, comparing this to freebsd it seems to be that most drivers > are compiled into the kernel and utilities such as ipfw/linux emu. are loaded as modules. > > I was wondering what the advantages/disadvantages are of using kernel modules as opposed to > compiling them in? advantages: you can update a module without rebooting a machine, if a bug was fixed in say the msdos filesystem module you could compile it, unload the existing module and load the newer version. vendors can distribute a binary module if they cant, or dont wish to release the source. lots of others. disadvantages: some drivers need to be able to allocate a large chunk of contiguous memory to operate correctly, this means some drivers cant work when not compiled in to the kernel (because they dont get their request for a block of memory in early enough). I was thinking about this recently, perhaps if the kernel allocated a chunk of memory early on in the boot process (amount configurable via sysctl) then this could be chopped up and handed to modules specifically, there is probably a good reason why this isnt possible (?) which has not occured to me, because it seems like the common sense solution. FreeBSD 5 will have many more things accessible via modules, a trend which is likely to continue. > If someone could kindly let me know or shout where theres an in-depth explanation on the net > I would be grateful :) > > Cheers, > > -- > Jamie Heckford > jamie@jamiesdomain.org.uk > http://www.jamiesdomain.org.uk/ > > FreeBSD: The Power to Serve > > -- > ____________________________________________________ > Message scanned for viruses and dangerous content by > <http://www.newnet.co.uk/av/>; and believed to be clean > > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message -- Dominic Marks Computer & Politics Geek [educ]::[umist.ac.uk] << notyet-known at umist.ac.uk >> [home]::[btinternet] << dominic_marks at btinternet.com >> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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