From: Michael Buesch <mb@bu3sch.de>
To: Russell King <rmk+lkml@arm.linux.org.uk>
Subject: Re: [RFC] [PATCH] Fix b43 driver build for arm
Date: Tue, 19 Feb 2008 00:17:04 +0100
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Cc: Gordon Farquharson <gordonfarquharson@gmail.com>,
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       stefano.brivio@polimi.it
References: <97a0a9ac0802181403ja79c32v864b093414b2755@mail.gmail.com> <20080218225354.GE23181@flint.arm.linux.org.uk> <20080218230058.GA32357@flint.arm.linux.org.uk>
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On Tuesday 19 February 2008 00:00:58 Russell King wrote:
> > > Why can't we have an array of this structure on ARM?
> > > 
> > > struct ssb_device_id {
> > >        __u16   vendor;
> > 
> > 2 bytes
> > 
> > >        __u16   coreid;
> > 
> > 2 bytes
> > 
> > >        __u8    revision;
> > 
> > 1 byte
> > 
> > > };
> > 
> > and therefore sizeof this structure will be 5 bytes, but because of the
> > ABI rules (which are _explicitly_ allowed by the C standard), it'll
> > become 8 bytes due to padding afterwards.
> 
> Another guess might be that, if using AEABI, this structure might
> be 6 bytes in size, but the linker will align structures to 4 bytes.

If the struct is padded to 6 bytes and the linker aligns it to 4 byte
everything will be naturally aligned, as far as I can see.

> FATAL: drivers/net/wireless/b43/b43: sizeof(struct ssb_device_id)=6 is
> not a modulo of the size of section __mod_ssb_device_table=64.
> Fix definition of struct ssb_device_id in mod_devicetable.h

So this message tells me the table size is 64 bytes. There are 8 entries,
so it seems the structure is padded to 8 bytes.
But above that it says that sizeof(struct ssb_device_id)=6

IMO this sanity check is broken and not the code.

Where does this sanity check message come from? The linker?

-- 
Greetings Michael.
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