Messages in this thread | | | Date | Fri, 3 Sep 2004 10:00:58 +0200 | From | Andi Kleen <> | Subject | Re: [discuss] f_ops flag to speed up compatible ioctls in linux kernel |
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On Wed, Sep 01, 2004 at 10:22:45AM +0300, Michael S. Tsirkin wrote: > Hello! > Currently, on the x86_64 architecture, its quite tricky to make > a char device ioctl work for an x86 executables. > In particular, > 1. there is a requirement that ioctl number is unique - > which is hard to guarantee especially for out of kernel modules
Yes, that is a problem for some people. But you should have used an unique number in the first place.
There are some hackish ways to work around it for non modules[1], but at some point we should probably support it better.
[1] it can be handled, except for module unloading, so you have to disable that.
> 2. there's a performance huge overhead for each compat call - there's > a hash lookup in a global hash inside a lock_kernel - > and I think compat performance *is* important.
Did you actually measure it? I doubt it is a big issue.
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