Re: Bug#609371: linux-image-2.6.37-trunk-sparc64: module scsi_mod: Unknown relocation: 36

[Richard Mortimer <richm@oldelvet.org.uk>]

On Sun, 2011-01-16 at 22:07 -0800, David Miller wrote:
> From: David Miller <davem@davemloft.net>
> Date: Sat, 15 Jan 2011 21:17:22 -0800 (PST)

> > I think the problem we have here is that the _ftrace_events section is
> > not aligned sufficiently.  That ".align 4" mnemonic is a good indication
> > of this.  It should at least "8" on sparc64.
> 
I noticed another potentially 64 bit unfriendly alignment on struct
tracepoint in include/linux/tracepoint.h. I don't think that the
alignment of 32 breaks anything but it does leave a 24 byte hole. I
don't know enough about tracing to know if that is necessary.

struct tracepoint {
        const char *name;               /* Tracepoint name */
        int state;                      /* State. */
        void (*regfunc)(void);
        void (*unregfunc)(void);
        struct tracepoint_func *funcs;
}  __attribute__((aligned(32)));        /*
                                         * Aligned on 32 bytes because it is
                                         * globally visible and gcc happily
                                         * align these on the structure size.
                                         * Keep in sync with vmlinux.lds.h.
                                         */

Note I spotted this when looking at some residual sparc64 relocation
issues when _ftrace_events alignment is changed to 8. I'll follow those
issues up in a separate email when I get time later today.

Regards

Richard