Hi. On Wed, Oct 22, 2008 at 9:44 PM, James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: > On Wed, 2008-10-22 at 21:25 +0200, Fabio Comolli wrote: >> Hi. >> >> On Wed, Oct 22, 2008 at 9:05 PM, James Bottomley >> <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx> wrote: >> > On Wed, 2008-10-22 at 18:29 +0200, Fabio Comolli wrote: >> >> Hi. >> >> In kernel 2.6.27.2 - drivers/scsi/Kconfig we have: >> >> >> >> config SCSI_WAIT_SCAN >> >> tristate >> >> default m >> >> depends on SCSI >> >> depends on MODULES >> >> >> >> The tristate field is empty. This has the effect that this option is >> >> not visible in menuconfig and so it's always selected. The default is >> >> "m" for all architectures and so this module is always compiled if >> >> SCSI and MODULES are both enabled. >> >> >> >> I'm using a patch like this one: >> >> >> >> config SCSI_WAIT_SCAN >> >> - tristate >> >> + tristate "Wait until all the async scans are complete" >> >> default m >> >> depends on SCSI >> >> depends on MODULES >> >> >> >> to get rid of that module. >> >> >> >> Of course, I have no idea if this is correct or the current behavior >> >> is the expected one. >> > >> > The point of all of this is that if you enable async scanning, you need >> > a method of waiting for the scans to complete, which is all this module >> > does (you insert it and it doesn't come back from the insertion until >> > all the pending async scans are complete). It's tristate because really >> > it only makes sense to be M or N. The consensus is that, given async >> > scanning is always an option, this function should always be built as a >> > module *if* modules and SCSI are enabled ... because you might have a >> > HBA module you enabled async scanning for and you need to wait. >> >> OK, I see your point. >> >> But in my case I have SCSI enabled only because it's SELECTed by ATA >> (it's just a laptop) and I don't have any hba's and never will. So no >> async scan. > > Presumably you have a laptop hard disk. That's currently SCSI if you > use ATA ... although when ATA moves out of SCSI it will no longer be, so > you could regard this as a temporary condition. Ok. > >> Maybe this module should be enabled if async scan is. > > But that's the point: async scan is always "enabled" it just might not > be the default, that's what the CONFIG_SCSI_SCAN_ASYNC controls: the > default value (but you can always turn it on with the kernel boot or > SCSI module option). Async scan is also functional for /drivers/ata and > other hot plug type busses, so it still makes sense for them as well. > I see the point. >> > There's really not much point giving the user the choice, since this >> > module is part of the initrd sequence ... it's not really anything a >> > user would want to use stand alone, hence there's no point giving a >> > choice about it. >> > >> >> I don't use initrd at all. I just noticed the existence of this module >> while trying to have a non modular kernel. This failed because of >> ipw2200 and after having enabled modules again I just found this >> scsi_wait_scan.ko. > > Well, we do use CONFIG_MODULES to try to discern whether the user wants > modules or not. However, if you enable modules, we'd need some > telepathic configurator to tell us if you plan to use SCSI HBA modules > or not, so the safest course is always to enable it. The real point is > that you have to be a real power user to answer N correctly to this, so > it's better not to confuse the remaining 97% with the option because > they could easily get wrong ... the 3% who're sure they don't want it > can simply delete it. > Thanks for your explanation. > James > Regards, Fabio > > -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
