svn commit: r258412 - in head/sys/arm: at91 econa s3c2xx0 sa11x0 xscale/i80321 xscale/i8134x xscale/ixp425 xscale/pxa

[John-Mark Gurney]

Andrew Turner wrote this message on Sat, Jan 11, 2014 at 13:51 +0000:
> On Fri, 10 Jan 2014 15:02:41 -0800
> John-Mark Gurney <jmg at funkthat.com> wrote:
> 
> > John-Mark Gurney wrote this message on Wed, Jan 08, 2014 at 09:39
> > -0800:
> > > So, I've tested that HEAD (absolutely no tree changes) w/
> > > WITHOUT_ARM_EABI boots fine...  and just to make sure my test is
> > > correct, I've disabled it too to verify that the kernel just hangs
> > > (absolutely no output)..  and reenabled it and verified it works
> > > (that my setting is changing something)...
> > > worky -> no worky -> worky...
> > > 
> > > Now I just realized another interesting thing about setting
> > > WITHOUT_ARM_EABI, it also fixes the console issue I was having w/
> > > your call to cpu_setup("") previously (w/ EABI) killing console
> > > output and not even seeing the mtx panic message...
> > > 
> > > So, it is clearly changing something very early on in boot...
> > 
> > Apparently gcc ARMEB w/ EABI miscompiles code...  The code to store
> > lo_flags in the lock_object is correct:
> >                         lock->lo_flags = i << LO_CLASSSHIFT;
> > c03ce2d0:       e1a01c06        lsl     r1, r6, #24
> > c03ce2d4:       e5881004        str     r1, [r8, #4]
> > 
> > But when I add a printf to fetch the data, I get:
> > printf("lo_classindex: %#x\n", LO_CLASSINDEX(lock));
> > c03ce2e0:       e5d81007        ldrb    r1, [r8, #7]
> > c03ce2e4:       e59f0098        ldr     r0, [pc, #152]  ; c03ce384
> > <_end+0xffcf9
> > 19c>
> > c03ce2e8:       e201100f        and     r1, r1, #15     ; 0xf
> > c03ce2ec:       eb0012ea        bl      c03d2e9c <printf>
> > 
> > 
> > We are doing a ldrb (LoaD Relative Byte) which would be fine to
> > substitute for the right shift of 24, but only if it loaded the
> > correct byte.. It should be loading #4 instead of #7 since we are on
> > big endian...
> > 
> > Anyone who know gcc arm well to figure this out?
> > 
> 
> I have an untested fix at [1]. As I don't have any big-endian boards I
> am unable to test the kernel with this.
> 
> Andrew
> 
> [1] http://people.freebsd.org/~andrew/armeb_gcc.diff

I have verified that this patch allows me to boot a kernel till it
mounts root...  As I haven't put together a root fs yet, I can't say
if it goes to single/multiuser yet...

Thanks!

-- 
  John-Mark Gurney				Voice: +1 415 225 5579

     "All that I will do, has been done, All that I have, has not."