[Top][All Lists]

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

[debbugs-tracker] bug#13332: closed ([PATCH] unbreak Emacs on Linux/M68K

From: GNU bug Tracking System
Subject: [debbugs-tracker] bug#13332: closed ([PATCH] unbreak Emacs on Linux/M68K)
Date: Wed, 02 Jan 2013 16:35:02 +0000

Your message dated Wed, 02 Jan 2013 17:33:24 +0100
with message-id <address@hidden>
and subject line Re: bug#13332: [PATCH] unbreak Emacs on Linux/M68K
has caused the debbugs.gnu.org bug report #13332,
regarding [PATCH] unbreak Emacs on Linux/M68K
to be marked as done.

(If you believe you have received this mail in error, please contact

13332: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=13332
GNU Bug Tracking System
Contact address@hidden with problems
--- Begin Message --- Subject: [PATCH] unbreak Emacs on Linux/M68K Date: Tue, 1 Jan 2013 22:51:12 +0100
Attempting to bootstrap Emacs 23.x or 24.x on Linux/M68K fails with
a SEGV as soon as temacs is run.  Inspecting the core dump shows:

Core was generated by `/home/mikpe/emacs-24.2/build-nox/src/temacs --batch 
--load loadu'.
Program terminated with signal 11, Segmentation fault.
#0  0x800d5444 in mark_object (arg=1174437910) at 
5720            if (CONS_MARKED_P (ptr))
(gdb) bt
#0  0x800d5444 in mark_object (arg=1174437910) at 
#1  0x800d55ba in mark_object (arg=-2143958762) at 
#2  0x800d5c3a in mark_vectorlike (ptr=0x8035b120) at 
#3  0x800d5d62 in Fgarbage_collect () at /home/mikpe/emacs-24.2/src/alloc.c:5128
#4  0x800eb7be in Ffuncall (nargs=3, args=0xefcdfad4) at 
#5  0x800ebc46 in call2 (fn=0, arg1=0, arg2=-2143972138) at 
#6  0x800ebf82 in Fsignal (error_symbol=0, data=-2143972138) at 
#7  0x800ec412 in xsignal (error_symbol=0, data=-2143972138) at 
#8  0x800ecdc8 in xsignal1 (error_symbol=0, arg=-2143955495) at 
#9  0x800ece32 in verror (m=0x8015f90d "Bad data in guts of obarray", 
ap=0xefce0b24) at /home/mikpe/emacs-24.2/src/eval.c:1998
#10 0x800ece44 in error (m=0x8015f90d "Bad data in guts of obarray") at 
#11 0x80108eec in oblookup (obarray=<optimized out>, ptr=0x80156383 
"char-table-extra-slots", size=22, size_byte=22) at 
#12 0x8010c578 in intern_c_string (str=0x80156383 "char-table-extra-slots") at 
#13 0x8005ce76 in init_category_once () at 
#14 0x80006558 in main (argc=<optimized out>, argv=0xefce0ef4) at 
(gdb) q

This turns out to be caused by the well-known issue of data alignment
on Linux/M68K: the ABI only aligns 32-bit (and larger) primitive types
to 16-bit boundaries, which doesn't provide enough known-zero bits in
object pointers for Emacs' tagging scheme, causing major confusion and
breakage at runtime.

This patch introduces two new integer types in src/m/m68k.h that are
exactly like int and unsigned int, except they are explicitly aligned
to 32-bit boundaries; gcc's attribute aligned is used for this purpose.
It then defines EMACS_INT and EMACS_UINT to these types to override the
default choices in src/lisp.h.

With this patch in place bootstrap succeeds and the final emacs
executable works fine.  Tested with Emacs-24.2 on Linux/M68K.

/Mikael Pettersson

[I consider this 6-line patch (not counting the comment) to be trivial so
I hope it will be acceptable even without a formal copyright assignment.]


2013-01-01  Mikael Pettersson  <address@hidden>

        * m/m68k.h [GNU_LINUX] (m68k_aligned_int_t, m68k_aligned_uint_t):
        New typedefs.

--- emacs-24.2/src/m/m68k.h.~1~ 2012-08-23 07:33:42.000000000 +0200
+++ emacs-24.2/src/m/m68k.h     2013-01-01 14:26:10.000000000 +0100
@@ -28,5 +28,19 @@ along with GNU Emacs.  If not, see <http
 #define DATA_SEG_BITS 0x80000000
+/* Define the type to use.
+   Emacs cannot use the default type (plain int) since the ABI on
+   Linux/M68K only aligns 32-bit (and larger) primitive types to
+   16-bit boundaries.  Define new explicitly aligned integer types
+   and use them for EMACS_INT and EMACS_UINT.  Compiling Emacs
+   with -malign-int does not work since it changes data layout in
+   external interfaces (system calls, libraries).  */
+typedef int m68k_aligned_int_t __attribute__ ((__aligned__ (4)));
+typedef unsigned int m68k_aligned_uint_t __attribute__ ((__aligned__ (4)));
+#define EMACS_INT m68k_aligned_int_t
+#define EMACS_UINT m68k_aligned_uint_t
+#define BITS_PER_EMACS_INT 32
+#define pI ""

--- End Message ---
--- Begin Message --- Subject: Re: bug#13332: [PATCH] unbreak Emacs on Linux/M68K Date: Wed, 02 Jan 2013 17:33:24 +0100 User-agent: Gnus/5.13 (Gnus v5.13) Emacs/24.2.91 (gnu/linux)
I just noticed that the commit didn't make it into 24.2.  But it should
be easy enough to backport for any interested parties.


Andreas Schwab, address@hidden
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

--- End Message ---

reply via email to

[Prev in Thread] Current Thread [Next in Thread]