[radeonhd] [Bug 20593] radeonhd driver generates unaligned traps on Alpha

11 Mar 2009

      http://bugs.freedesktop.org/show_bug.cgi?id=20593

--- Comment #2 from Ales Fiala   2009-03-11 12:41:35 PST ---
Most, if not all, of these unaligned accesses are in the AtomBIOS. This is just
initialization code that is not performance critical. So if you can put up with
the polluted kernel logs, I don't think it is much of a problem.

I am running into the same problem on the Itanium processor but I also have
endianness problem with the same accesses. I started wrapping them all in a
macro.

Ales Fiala

bugzilla-daemon@freedesktop.org wrote:
...
http://bugs.freedesktop.org/show_bug.cgi?id=20593
Summary: radeonhd driver generates unaligned traps on Alpha
           Product: xorg
           Version: git
          Platform: Alpha
        OS/Version: Linux (All)
            Status: NEW
          Severity: minor
          Priority: low
         Component: Driver/radeonhd
        AssignedTo: lverhaegen@suse.de
        ReportedBy: mcree@orcon.net.nz
         QAContact: xorg-team@lists.x.org
                CC: mcree@orcon.net.nz
The radeonhd driver generates unaligned traps on Alpha architecture.  These are
not a show stopper, but do incur very inefficient memory accesses via kernel
traps, and pollute the kernel logs with annoying messages.
Using radeonhd at git  df71658688e47614a3f660c28ac1dc77970eb491
But the version is irrelevant as the misaligned memory accesses have been there
for a long time - I have been too lazy to report them until now.
...
From dmesg:
X(2015): unaligned trap at 0000020000903088: 000002000098c5d7 28 1
X(2015): unaligned trap at 0000020000903088: 000002000098c5df 28 1
X(2015): unaligned trap at 0000020000903088: 000002000098c5e7 28 1
X(2015): unaligned trap at 0000020000903088: 0000020000989771 28 1
Connecting gdb to the running X process reveals the culprit:
(gdb) list *0x0000020000903088
0x20000903088 is in GetParametersDirect32 (AtomBios/CD_Operations.c:441).
436     }
437     
438     UINT32 GetParametersDirect32(PARSER_TEMP_DATA STACK_BASED *    
pParserTempData)
439     {
440         pParserTempData->CD_Mask.SrcAlignment=alignmentDword;
441        
pParserTempData->Index=*(UINT32*)pParserTempData->pWorkingTableData->IP;
442         pParserTempData->pWorkingTableData->IP+=sizeof(UINT32);
443         return pParserTempData->Index;
444     }
445
Line 441 is a 32bit (long word) access.  The address dereferenced is not
aligned to a 32bit boundary for an unaligned trap to occur.
The ati driver is worse.  It coughs up unaligned traps from
GetParametersDirect16() and GetParametersRegister() too, but I haven't seen
these from radeonhd.
Cheers
Michael.
-- 
Configure bugmail: http://bugs.freedesktop.org/userprefs.cgi?tab=email
------- You are receiving this mail because: -------
You are the QA contact for the bug.
_______________________________________________
xorg-team mailing list
xorg-team@lists.x.org
http://lists.x.org/mailman/listinfo/xorg-team
-- 
To unsubscribe, e-mail: radeonhd+unsubscribe@opensuse.org
For additional commands, e-mail: radeonhd+help@opensuse.org

[radeonhd] [Bug 20593] radeonhd driver generates unaligned traps on Alpha

bugzilla-daemon＠freedesktop.org