Re: Device Drivers and Kernel Modules
Lowell, Thanks for the reply. Sorry about the belated gratitude. I haven't checked the account in a while and simply forgot I posted the question. I think I got confused in my memory. Now what I think I read was about filesystem kernel modules. From my understanding these could be automatically loaded through the mount command. At least, thats the author's claim in FreeBSD Unleashed. Just to be more specific this inquiry is NOT for a server. It is my experimental desktop at home. Servers I would agree have no need to be convenient in swapping hardware. But I do switch out hardware on the system in question occasionally and was really just curious if there is a drawback between the drivers in the kernel opposed to loaded kernel modules. Thanks again David Wassman On 9/5/06, Lowell Gilbert [EMAIL PROTECTED] wrote: David Wassman [EMAIL PROTECTED] writes: I am trying to figure out which would be best, to load all the device drivers through compiling them into the kernel or to load them at boot through loader.conf. I would think that loader.conf would be more convenient as changing hardware wuld not require a rebuild of the kernel. Is there a draw back to loading devices this way other than a longer boot up time (which should not be an issue as the system is 24-7)? There is little difference for your purposes. I have also heard that loading modules through the loader.conf saves on RAM performance as the module in question is not loaded into memory until it is used as opposed to being loaded with the kernel. If this makes no sense, i appologize. I remember reading it somewhere on a mailing list several years ago and can't find the reference anymore. From memory it stated modules such as cd9660 could be loaded through entering CD9660_load=YES in loader.confand that it would not be used in memory until a cd was mounted. I am assuming this is true (if it is) for other modules as well. It isn't true at all. Loading a module really does load it into memory. -- Lowell Gilbert, embedded/networking software engineer, Boston area http://be-well.ilk.org/~lowell/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Device Drivers and Kernel Modules
David Wassman [EMAIL PROTECTED] writes: I am trying to figure out which would be best, to load all the device drivers through compiling them into the kernel or to load them at boot through loader.conf. I would think that loader.conf would be more convenient as changing hardware wuld not require a rebuild of the kernel. Is there a draw back to loading devices this way other than a longer boot up time (which should not be an issue as the system is 24-7)? There is little difference for your purposes. I have also heard that loading modules through the loader.conf saves on RAM performance as the module in question is not loaded into memory until it is used as opposed to being loaded with the kernel. If this makes no sense, i appologize. I remember reading it somewhere on a mailing list several years ago and can't find the reference anymore. From memory it stated modules such as cd9660 could be loaded through entering CD9660_load=YES in loader.confand that it would not be used in memory until a cd was mounted. I am assuming this is true (if it is) for other modules as well. It isn't true at all. Loading a module really does load it into memory. -- Lowell Gilbert, embedded/networking software engineer, Boston area http://be-well.ilk.org/~lowell/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
Re: Device Drivers and Kernel Modules
--- Lowell Gilbert [EMAIL PROTECTED] wrote: David Wassman [EMAIL PROTECTED] writes: I am trying to figure out which would be best, to load all the device drivers through compiling them into the kernel or to load them at boot through loader.conf. I would think that loader.conf would be more convenient as changing hardware wuld not require a rebuild of the kernel. Is there a draw back to loading devices this way other than a longer boot up time (which should not be an issue as the system is 24-7)? There is little difference for your purposes. I have also heard that loading modules through the loader.conf saves on RAM performance as the module in question is not loaded into memory until it is used as opposed to being loaded with the kernel. If this makes no sense, i appologize. I remember reading it somewhere on a mailing list several years ago and can't find the reference anymore. From memory it stated modules such as cd9660 could be loaded through entering CD9660_load=YES in loader.confand that it would not be used in memory until a cd was mounted. I am assuming this is true (if it is) for other modules as well. It isn't true at all. Loading a module really does load it into memory. -- Lowell Gilbert, embedded/networking software engineer, Boston area http://be-well.ilk.org/~lowell/ ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED] In general if it is hot pluggable modules are the best with the appropriate configurations in the daemons that track hardware changes. If it won't come out during the system running then in the kernel is the best. Unless your running an old system recompiling a kernel is 15 minutes of time away. And since its a server you likely will not be constantly updating your base, but even still a new world and kernel should only be an hour tops away, unless you using older equipment. Generally Cardbus/PCMCIA cards you would want modules so you can save a second or two booting and a few k of RAM have them load and unload as needed, Gvinum is recommended as a module so you can restart it, USB dongles (bluetooth and such) and what not (although drives I generally put in the kernel) Personally I put all the hardware I plan on using in the kernel because it can make life slightly easier. That and unless your doing embedded development or running a 486 you will probably have enough RAM for the additional overhead. In a server scenario your going to be pluggin in hard drives which is and should be built it. I doubt your going to have a sound card, and probably not even DRI modules to contend to. You should have enough RAM where having everything in the kernel isn't going to matter much. This DOES NOT mean use every option when building, but if your server has the hardware, enable it. I believe using modules uses slightly more RAM because the kernel needs the hooks to the module and then the module on top of the hooks, versus just having the code in the kernel, but this is my understanding of things. -brian ___ freebsd-questions@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-questions To unsubscribe, send any mail to [EMAIL PROTECTED]
