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Re: -mm merge plans for 2.6.21

To: Ralf Baechle <>
Subject: Re: -mm merge plans for 2.6.21
From: Davide Libenzi <>
Date: Sat, 10 Feb 2007 20:53:52 -0800 (PST)
Cc: David Woodhouse <>, Heiko Carstens <>,, Andrew Morton <>, Alexey Dobriyan <>, Linux Kernel Mailing List <>, Ulrich Drepper <>
In-reply-to: <>
Original-recipient: rfc822;
References: <> <> <> <> <> <> <> <>
On Sat, 10 Feb 2007, Ralf Baechle wrote:

> Unfortunately struct epoll_event contains a gap so it bets on identical
> padding rules between native and compat ABI and anyway, padding is wasted
> space so the struct members should have been swapped when this structure
> was created.  Oh well, too late.

You really should have needed padding in there, since even if you swapped 
the members, sizeof(struct epoll_event) would still need to be 16, if 
alignof(u64) == 8. Either adding an extra auxilliary u32, or make the two 
members be u64, would have been ok.
I'll be posting a patch that adds the compat_ layer for epoll in 
kernel/compat.c. Architectures that needs it (currently only ARM-EABI and 
IA64 use a compat code for epoll), should wire them up.

- Davide

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