Date: Sat, 11 Jan 2014 13:51:56 +0000 From: Andrew Turner <andrew@fubar.geek.nz> To: John-Mark Gurney <jmg@funkthat.com> Cc: andrew@FreeBSD.org, freebsd-arm@FreeBSD.org, Ian Lepore <ian@FreeBSD.org> Subject: Re: svn commit: r258412 - in head/sys/arm: at91 econa s3c2xx0 sa11x0 xscale/i80321 xscale/i8134x xscale/ixp425 xscale/pxa Message-ID: <20140111135156.251a70fa@bender.Home> In-Reply-To: <20140110230241.GS46596@funkthat.com> References: <201311210108.rAL18AoQ051365@svn.freebsd.org> <20131221061048.GC99167@funkthat.com> <20140108071643.GB99167@funkthat.com> <1389197091.1158.370.camel@revolution.hippie.lan> <20140108173909.GF99167@funkthat.com> <20140110230241.GS46596@funkthat.com>
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On Fri, 10 Jan 2014 15:02:41 -0800
John-Mark Gurney <jmg@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
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