Laurie Jennings via freebsd-net wrote this message on Wed, Jul 29, 2015 at
15:26 -0700:
>
> I have a problem and I can't quite figure out where to look. This is what Im
> doing:
>
> I have an IOCTL to read a block of data, but the data is too large to return
> via ioctl. So to get the data,
> I allocate a block in a kernel module:
>
> foo = malloc(1024000,M_DEVBUF,M_WAITOK);
>
> I pass up a pointer and in user space map it using /dev/kmem:
An easier solution would be for your ioctl to pass in a userland
pointer and then use copyout(9) to push the data to userland... This
means the userland process doesn't have to have /dev/kmem access...
Is there a reason you need to use kmem? The only reason you list above
is that it's too large via ioctl, but a copyout is fine, and would
handle all page faults for you..
--
John-Mark Gurney Voice: +1 415 225 5579
"All that I will do, has been done, All that I have, has not."
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