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Hi Larry
I am not an expert in the internal of kernel device drivers but I need to
contact someone who is and who can help me. The help desk staff at RedHat do not
seem to have the necessary levels of expertise to sort out what is a very real
problem with the linux kernels and in particular the differences between
2.0.36-0.7 (Linux 5.2) and 2.2.5-15 (Linux 6.0). My problem is that the kernels
do not seem to be upwardly compatible.
I have a system which uses a modern BX board with built in AIC 7895 scsi
controllers on which I have three scci 4.3 scci disks mounted. I also have an
LS120 drive with a standard floppy. The reason for my upgrading from 5.2 to 6.0
was because of timeout problems on the scci bus where the 2.0.36 kernel keeps
resetting after a timeout. The 6.0 system appears to be better in this respect
but using the 2.2.5-15 kernel gives rise to more serious problems namely that
the parallel port does not appear to have been configured in the kernel and I
cannot gain access to my LS120 drive because it is not prperly detected by the
system.
The essential fault appears to lie in the
specification of the /proc/devices directory which is a virtual file system
which forms part of the kernel. If you examine this directory on both the
2.0.36-07 (Linux Version 5.2) and 2.2.5-15 (Linux Version 6.0) kernels you will
see that they are very different and that the key 'lp' item is missing from
the 2.2.5-15 kernel. The label for the 'lp' item is 6 which I believe to be the
major port number in the 'major minor' number port identifier sequence. The way
in which the /proc directory is used by the rest of the system is critical but I
have yet to find any documentation on this. To put matters right you would need
to rebuild the kernel but Redhat do not provide the means to do this or of
copies of the make files from which the kernels were originally constructed, so
that their construction can be verified against their specification.
Doing a cat on the /proc/devices virtual directory
for kernel 2.2.5-15
gave the following results
Character devices: Block devices: 1 mem 1 ramdisk 2 pty 2 fd 3 ttyp 3 ide0 4 ttyS 8 sd 5 cua 9 md 7 vcs 22 ide1 10 misc 29 fb 36 netlink 128 ptm 136 pts The corresponding values for the 2.0.36-07 kernel were Character devices: Block devices: 1 mem 1 ramdisk 2 pty 2 fd 3 ttyp 3 ide0 4 ttyp 8 sd 5 cua 9 md 6 lp 22 ide1 7 vcs 10 misc While the Block devices are the same
the Character Devices differ significantly
I attach a copy of my correspondence with the RedHat Help desk
Thanks
Gerry Hooper
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