xorg-server : fails to compile for MIPS64 n32

[Vicente Olivert Riera]

Hello,

could some Xorg developer have a look to this patch? (is at the bottom
of this email)

That patch has been attached to the following bug report:

https://bugs.freedesktop.org/show_bug.cgi?id=79939

Please CC me in the replies because I'm not subscribed to the list.

Thanks.
-- 
Vicente Olivert Riera
Graduate Software Engineer, MIPS Platforms
Imagination Technologies Limited
t: +44 (0)113 2429814
www.imgtec.com

On 12/04/2014 09:09 PM, Peter Hutterer wrote:
> On Thu, Dec 04, 2014 at 12:36:32PM +0000, Vicente Olivert Riera wrote:
>> On 12/04/2014 12:09 AM, Peter Hutterer wrote:
>>> On Wed, Dec 03, 2014 at 12:05:57PM +0000, Vicente Olivert Riera wrote:
>>>> Dear Peter Hutterer,
>>>>
>>>> could you please have a look to this bug report:
>>>>
>>>> https://bugs.freedesktop.org/show_bug.cgi?id=79939
>>>
>>> please send the patch to xorg-devel where it will (hopefully) get some
>>> review
>>
>> Do the Xorg developers do not care about the bug reports?
> 
> development is done via the mailing list, if you already have a patch the
> chances that someone reviews it when it lands on the list are higher than
> 'hidden' away in some bugreport.
> 
> Cheers,
>    Peter
> 
> 

>From cead7d51f3e014e04ae6e2f7c6ca332df5415b71 Mon Sep 17 00:00:00 2001
From: Vicente Olivert Riera <Vincent.Riera at imgtec.com>
Date: Wed, 3 Dec 2014 11:34:47 +0000
Subject: [PATCH] backtrace.c: Fix word cast to a pointer

backtrace.c uses a word size provided by libunwind. In some
architectures like MIPS, libunwind makes that word size 64bit.

In the lines #90 and #98, backtrace.c tries to do a cast to a pointer,
which in some architectures may fail, like MIPS64 n32 for instance,
because the size of the pointers is not 64bit wide:

Making all in os
make[2]: Entering directory
`/home/test/test/1/output/build/xserver_xorg-server-1.15.1/os'
  CC     WaitFor.lo
  CC     access.lo
  CC     auth.lo
  CC     backtrace.lo
backtrace.c: In function 'xorg_backtrace':
backtrace.c:90:20: error: cast to pointer from integer of different size
[-Werror=int-to-pointer-cast]
	 if (dladdr((void *)(pip.start_ip + off), &dlinfo) &&
dlinfo.dli_fname &&
		    ^
backtrace.c:98:13: error: cast to pointer from integer of different size
[-Werror=int-to-pointer-cast]
	     (void *)(pip.start_ip + off));
	     ^
cc1: some warnings being treated as errors
make[2]: *** [backtrace.lo] Error 1
make[2]: *** Waiting for unfinished jobs....

Making the cast to a pointer-sized integer, and then to a pointer fixes
the problem.

Related:
  https://bugs.freedesktop.org/show_bug.cgi?id=79939

Signed-off-by: Vicente Olivert Riera <Vincent.Riera at imgtec.com>
---
 os/backtrace.c |    4 ++--
 1 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/os/backtrace.c b/os/backtrace.c
index 3d1195b..3c101ae 100644
--- a/os/backtrace.c
+++ b/os/backtrace.c
@@ -87,7 +87,7 @@ xorg_backtrace(void)
             procname[1] = 0;
         }

-        if (dladdr((void *)(pip.start_ip + off), &dlinfo) &&
dlinfo.dli_fname &&
+        if (dladdr((void *)(long)(pip.start_ip + off), &dlinfo) &&
dlinfo.dli_fname &&
                 *dlinfo.dli_fname)
             filename = dlinfo.dli_fname;
         else
@@ -95,7 +95,7 @@ xorg_backtrace(void)

         ErrorFSigSafe("%u: %s (%s%s+0x%x) [%p]\n", i++, filename, procname,
             ret == -UNW_ENOMEM ? "..." : "", (int)off,
-            (void *)(pip.start_ip + off));
+            (void *)(long)(pip.start_ip + off));

         ret = unw_step(&cursor);
         if (ret < 0)
-- 
1.7.1