Hi,
Please reply to the mailing list also. See inline:
manikandan wrote:
hi,
In "Advanced Char Driver Operations" Chapter in LDD by Alessandro
Rubini. ,some macros like _IOC_NONE , _IOC_READ,_IOC_WRITE, and
_IOC_READ | _IOC_WRITE are given to frame commands.
the above mentioned indicate the direction of data transfer.
If Interpretation of commands must be same in user space and kernel
space and if we r using these macros and dynamically allocating
value,then how user space will know this..(these macros can't be used
in user space know)
AFAIK commands are interpreted based on the magic numbers
(ioctl-number.txt) used to define
an ioctl command. The macros _IOC_READ, _IOC_WRITE are interpreted only
when there is a data transfer involved when issuing a particular ioctl
command.
Rgds
B.M.K
hiran wrote:
manikandan wrote:
hi,
what is the method to follow for framing numbering for ioctl
commands...
what are the drawbacks if i follow sequence numbering starting
from some 25 or 35...
ioctl command numbers should be unique across the whole system. For
details refer to "Advanced Char Driver Operations" Chapter in LDD by
Alessandro Rubini.
Rgds
B.M.K
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