RE: scripts/mod/file2alias.c cross compile problem

From: Rusty Russell
Date: Thu Aug 02 2007 - 18:09:13 EST


On Thu, 2007-08-02 at 09:25 -0700, Luck, Tony wrote:
> > Adrian Bunk: scripts/mod/file2alias.c is compiled with HOSTCC and ensures that
> > kernel_ulong_t is correct, but it can't cope with different padding on
> > different architectures.
>
> Surely this is the root cause ... you can't expect that the alignment
> rules of HOSTCC to make any sense for an arbitraty target.
>
> > +#define FILLUP_LEN 7 /* dirty fix for i386 -> 64bit cross-compilation */
> >
> > struct acpi_device_id {
> > __u8 id[ACPI_ID_LEN];
> > + __u8 dummy[FILLUP_LEN];
> > kernel_ulong_t driver_data;
> > };
>
> What's so special about this structure that we get an error?

It's in mod_devicetable.h: see comment at top of that file. These
structures serve dual purpose: to describe the capabilities of the
driver to the kernel probing functions, *and* to export them to
userspace tables. The former purpose is why there's a data pointer in
there.

scripts/mod/file2alias is the program that reads this: although it can
be altered to parse 32-vs-64, Adrian's fix is the simplest.

Hope that clarifies,
Rusty.

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