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1c4800743d
Updated Makefile to automatically generate bootscript and udev-config tarballs Updated licesnse to be the same as BLFS git-svn-id: http://svn.linuxfromscratch.org/LFS/trunk/BOOK@8548 4aa44e1e-78dd-0310-a6d2-fbcd4c07a689
34 lines
1.5 KiB
Plaintext
34 lines
1.5 KiB
Plaintext
Purpose of rules file:
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The kernel does not always fully populate a given kobject's attributes before
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sending the uevent for that kobject. This means that a given sysfs directory
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may not have all the required files in it (each directory corresponds to a
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kobject, and each file corresponds to an attribute).
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Therefore, we must sometimes wait for attributes to show up when devices are
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discovered. This is accomplished by udev's WAIT_FOR_SYSFS rule types.
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Description of rules:
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All rules in this file match ACTION="add", because none of them apply when
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devices are being removed.
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SUBSYSTEM is the kernel subsystem that the device uses. Current kernels have
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some issues with SCSI device attributes being created too late. For any device
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with a SUBSYSTEM of scsi, we must wait for the ioerr_cnt attribute. (This is
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the last attribute created for SCSI devices, so when this attribute appears,
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the kobject is fully populated.)
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It is also possible to use SUBSYSTEMS in Udev rules. Using SUBSYSTEMS would
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cause Udev to search up the device tree for a matching SUBSYSTEM value. (Note
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that "the device tree" is not necessarily the same as the path under /sys (the
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DEVPATH). Rather, "up the device tree" is the path followed by udevinfo when
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it is given the argument "-a".)
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We do not use SUBSYSTEMS in this rule, because we only care about the SUBSYSTEM
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of the kobject in question. We don't care about devices that are children of
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SCSI devices, only the SCSI device itself. We will use SUBSYSTEMS in later
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rules, though.
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