Date: Mon, 2 Jul 2007 13:47:16 +0300 From: Nikolay Pavlov <quetzal@zone3000.net> To: "M. Warner Losh" <imp@bsdimp.com> Cc: current@freebsd.org, marck@rinet.ru, nate@root.org Subject: Re: GEOM weirdness with SD flash reader? Message-ID: <20070702104716.GB13720@zone3000.net> In-Reply-To: <20070701.221911.1394573729.imp@bsdimp.com> References: <46880F1C.3020602@root.org> <20070701.215557.1373430453.imp@bsdimp.com> <4688791D.6050007@root.org> <20070701.221911.1394573729.imp@bsdimp.com>
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On Sunday, 1 July 2007 at 22:19:11 -0600, M. Warner Losh wrote: > In message: <4688791D.6050007@root.org> > Nate Lawson <nate@root.org> writes: > : M. Warner Losh wrote: > : > In message: <46880F1C.3020602@root.org> > : > Nate Lawson <nate@root.org> writes: > : > : Yes, you're exactly right. However, shouldn't a read from a device > : > : trigger a re-taste if the media is removable? > : > > : > I don't think it does. The driver is expected to poll, however... > : > > : > : So the fdisk of da2 > : > : should have caused it to re-read the MBR and create /dev/da2s1. I think > : > : maybe there should be a flag set for devices with removable media that > : > : causes the device to be re-tasted on every mount request. > : > > : > Is there even a removable flag to disks? > : > : In SCSI there is, removable flag combined with medium not present: > : > : da2 at umass-sim1 bus 1 target 0 lun 2 > : da2: <Generic STORAGE DEVICE 0001> Removable Direct Access SCSI-0 device > : ^^^^^^^^^ > : da2: 40.000MB/s transfers > : da2: Attempt to query device size failed: NOT READY, Medium not present > > I think you've misunderstood my point. I know that SCSI has this > flag, but I can't find anything in GEOM that it would map to. It > seems a common enough situation that having such a flag in GEOM would > be beneficial and easy to implement. > > : What if we kicked off a thread to run every 3 seconds that did a quick > : poll of such devices and sent a devd notify if they arrived (i.e. medium > : present)? It wouldn't work for floppy drives, but we could make this > : part of the da driver or something in usermode like devd itself calling > : camcontrol? > > In the past, people have said that polling messes up multimedia > access, so it hasn't happened. > > But wouldn't a simple daemon in userland do the same thing? Or > parsing the output of camcontrol inquiry? Camcontrol rescan is a nop > for these devices. Hald is using the same tactic. My dmesg is full of poll messages when i am using cardreader with it. -- ====================================================================== - Best regards, Nikolay Pavlov. <<<----------------------------------- ======================================================================
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