android neon detection busticated
Bug #911860 reported by
Tom Gall
This bug affects 1 person
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
libjpeg-turbo |
Triaged
|
Undecided
|
Tom Gall |
Bug Description
hwcap.h and link.h appears to be both missing from Android ICS.
The old NEON detection is fragile.
We need a newer and more reliable method of detecting if NEON is available for use on Android.
Changed in libjpeg-turbo: | |
assignee: | nobody → Tom Gall (tom-gall) |
milestone: | none → 1.1.90-2012.01 |
status: | New → Triaged |
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Just a quick comment based on what I see in http:// bazaar. launchpad. net/~ubuntu- branches/ ubuntu/ precise/ libjpeg- turbo/precise/ view/3/ simd/jsimd_ arm.c:
Yes, the current code looks a bit dodgy... you'll need to open /proc/self/auxv instead of trying to find the auxv data by scanning from envp.
Except in native assembler programs which do not use a C library, there's no guarantee that the auxv data will be present at the end of the environment since the C library may have overwritten or moved the initial environment block since the process started. AFAIK, libc doesn't provide any API for getting at the auxv data, so reading /proc/self/auxv or /proc/cpuinfo is the only option (and /proc/self/auxv has a more fixed, easier-to-parse format)