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

From: Thomas Renninger
Date: Thu Aug 16 2007 - 10:27:47 EST


On Fri, 2007-08-03 at 08:08 +1000, Rusty Russell wrote:
> 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.

Oops, this will cause a lot build warnings, as this struct gets
initialized like that:
..
{"PNP0C0A", 0},
..
at a lot places. It would be better to bump up the id itself like the
attached patch does...

Thanks,

Thomas

----------------------

Cross-compilation between e.g. i386 -> 64bit could break -> work around it

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.

Signed-off-by: Thomas Renninger <trenn@xxxxxxx>

---
include/linux/mod_devicetable.h | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)

Index: linux-2.6.23-rc3/include/linux/mod_devicetable.h
===================================================================
--- linux-2.6.23-rc3.orig/include/linux/mod_devicetable.h
+++ linux-2.6.23-rc3/include/linux/mod_devicetable.h
@@ -159,7 +159,8 @@ struct ap_device_id {

#define AP_DEVICE_ID_MATCH_DEVICE_TYPE 0x01

-#define ACPI_ID_LEN 9
+#define ACPI_ID_LEN 16 /* only 9 bytes needed here, 16 bytes are used */
+ /* to workaround crosscompile issues */

struct acpi_device_id {
__u8 id[ACPI_ID_LEN];


-
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/