Messages in this thread | | | From | Arnd Bergmann <> | Subject | Re: [PATCH 1/6] GenWQE PCI support, health monitoring and recovery | Date | Thu, 5 Dec 2013 21:31:42 +0100 |
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On Thursday 05 December 2013, Frank Haverkamp wrote: > > > Was wrong, as already pointed out before. It is now: > > > > > > struct genwqe_mem { > > > __u64 addr; > > > __u64 size; > > > int direction; > > > }; > > > > > > I hope the int is ok here. > > > > No, it's not. The problem is that sizeof(struct genwqe_mem) is now 24 on > > most architectures (including x86-64) and 20 on x86-32. > > Interesting. So int is like long architecture specific. I changed it to > be __u64 too, to avoid any problem.
The solution is ok, but the problem is different from what you thought:
On all architectures that Linux runs on, 'int' is 32 bit. The problem is again the alignment of __u64. On normal architectures, it is naturally aligned, and gcc adds 4 byte padding so that 'sizeof (struct genwqe_mem)' is multiple of the required alignment. On x86-32, the required alignment for the __u64 members is only 4 bytes, so no padding is added.
Arnd
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