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SubjectRe: Right way to configure a driver? (sysfs, ioctl, proc, configfs,....)

On Wed, 1 Feb 2006, Aritz Bastida wrote:

>>> 3.- Actually the most difficult config I must do is to pass three
>>> values from userspace to my module. Specifically two integers and a
>>> long (it's an offset to a memory zone I've previously defined)
>>> struct meminfo {
>>> unsigned int id; /* segment identifier */
>>> unsigned int size; /* size of the memory area */
>>> unsigned long offset; /* offset to the information */
>>> };
>>> How would you pass this information in sysfs? Three values in the same
>>> file? Note that using three different files wouldn't be atomic, and I
>>> need atomicity.
>> Use configfs.
> Ummhh, and would it be correct to configure my device via a netlink
> socket? Remember that my driver is a kind of network "virtual" device.
> There are so many old and new ways to configure a driver that I'm a
> bit overwhelmed...
> Regards
> Aritz

At the risk of the obvious....
struct meminfo meminfo;
ioctl(fd, UPDATE_PARAMS, &meminfo);

... and define UPDATE_PARAMS and other function codes to start
above those normally used by kernel stuff so that `strace` doesn't
make up stories.

This is what the ioctl() interface is for. Inside the kernel
you can use spinlocks (after you got the data from user-space)
to make the operations atomicc.

Dick Johnson
Penguin : Linux version on an i686 machine (5589.66 BogoMips).
Warning : 98.36% of all statistics are fiction.
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