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Bug 4835

Summary: Default for SDL_SIMDAlignment causes crashes on some 64-bit systems
Product: SDL Reporter: Simon Howard <fraggle+libsdl>
Component: mainAssignee: Ryan C. Gordon <icculus>
Status: RESOLVED FIXED QA Contact: Sam Lantinga <slouken>
Severity: normal    
Priority: P2 CC: icculus
Version: 2.0.10Keywords: target-2.0.12
Hardware: Other   
OS: OpenBSD   
Attachments: Patch to fix bug.

Description Simon Howard 2019-10-21 01:52:59 UTC 
Created attachment 3989 [details]
Patch to fix bug.

In SDL_cpuinfo.c the default value for SDL_SIMDAlignment is set to 4 unless system-specific CPU features are detected. This can cause SDL_SIMDAlloc() to crash on MIPS64 systems because memory is allocated on 4-byte boundaries, but MIPS64 requires 8-byte alignment (unaligned accesses cause a Bus Error).

Changing to sizeof(void *) should make for a safer default and fixes the crash. Diff attached.
Comment 1 Ryan C. Gordon 2019-10-21 02:19:54 UTC 
Your patch is now https://hg.libsdl.org/SDL/rev/568f67c04841, thanks!

--ryan.