Messages in this thread | ![/](/images/icornerl.gif) | | Subject | Re: [RFC][PATCH] perf: sysfs type id | From | Michael Ellerman <> | Date | Wed, 10 Nov 2010 14:37:33 +1100 |
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On Wed, 2010-11-10 at 02:59 +0100, Kay Sievers wrote: > On Wed, Nov 10, 2010 at 02:45, Michael Ellerman <michael@ellerman.id.au> wrote: > > On Wed, 2010-11-10 at 02:19 +0100, Kay Sievers wrote: > >> On Wed, Nov 10, 2010 at 02:10, Michael Ellerman <michael@ellerman.id.au> wrote: > >> > On Wed, 2010-11-10 at 01:57 +0100, Kay Sievers wrote: > >> >> Stay on the list please, with any possible reply. Thanks! > >> > > >> > You dropped the CC when you replied, or is my mailer being weird? > >> > >> You replied to me only: > >> From: Michael Ellerman <michael@ellerman.id.au> > >> To: Kay Sievers <kay.sievers@vrfy.org> > > > > Because you replied to me only, or at least that's what I see at my end. > > Sure, I don't add lists back when people reply to me only. You never > know why they do that, and if they have a reason for it. That's why I > added the the same mail: > "Stay on the list please, with any possible reply. Thanks!" > > >> Devices can never be on two subsystems at the same time. Not with > >> classes, not with buses, that was never, and probably will never be > >> possible. > > > > OK, I guess I'm getting my terminology wrong. My devices, which show up > > in /sys/class/foo are symlinks into /sys/devices/virtual/foo, so they > > _appear_ to be in two places. > > > > I also see entries for example in /sys/class/scsi_disk that link > > into /sys/devices/pci. > > Sure, all devices (devices are real directories) end up in the tree in > /sys/devices/. That's one tree, where all the devices from different > subsystems stack on top of others. > > > All devices have a symlink called 'subsystem' which points back to the > individual class the device belongs to. > > To find all device of a specific subsystem, you start at the subsystem > directory (class/bus) which collects them (only symlinks to the > device, not directories). > > That way you will find a blockdev, even when it's deep down in a chain > of devices: > pci:bridge/pci:dev/scsi:host/scsi:target/scsi:lun/block
OK, I think I get it. Thanks for taking the time to explain it to me :)
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