Messages in this thread | | | Subject | Re: [PATCH 01/13] [RFC] ipath basic headers | From | Andi Kleen <> | Date | 18 Dec 2005 04:25:27 +0100 |
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ebiederm@xmission.com (Eric W. Biederman) writes:
> Christoph Hellwig <hch@infradead.org> writes: > > > please always used fixes-size types for user communication. also please > > avoid ioctls like the rest of the IB codebase. > > Could someone please explain to me how the uverbs abuse of write > is better that ioctl?
It's actually worse because if they have a 32bit compat issue then ioctl can be fixed up, but read/write can't.
I wish the people arguing against ioctl all the time would just stop that because the alternatives are usually worse.
> - 64bit compilers will not pad every structure to 8 bytes. This > only will happen if you happen to have an 8 byte element in your > structure that is only aligned to 32bits by a 32bit structure. > Unfortunately the 32bit gcc only aligns long long to 32bits on > x86, which triggers the described behavior.
Exactly - and driver writers usually don't get that right so we need to have a tool to fix it up in the end. And with ioctl that's easiest.
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