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Rockbox mail archiveSubject: Re: Segfault with Faster MDCT patch and -fPICRe: Segfault with Faster MDCT patch and -fPIC
From: Dave Hooper <dave_at_beermex.com>
Date: Sun, 10 Oct 2010 11:35:11 +0100 I hope to take a look today > On 17.09.2010 09:32, Slawomir Testowy wrote: >> Hi all! >> >> For some time I have been using tremor with fastermdct patch found on >> http://www.rockbox.org/wiki/FasterMDCT. This patch gives huge speedup on >> i686/x86_64 machines and smaller, but still significant, speedup on ARM. >> >> Everything works great until I compile tremor on ARM with -fPIC flag (I link >> tremor into a shared object). In such case it segfaults in macro TRANSFORM_EQUAL >> in file fft-ffmpeg_arm.h at line 158: >> >> asm volatile( "ldmia %[my_z], {%[t5],%[t6]}\n\t":[t5] "=r" (t5), [t6] "=r" >> (t6):[my_z] "r" (z));\ >> >> When I compile tremor without -fPIC or with -U_ARM_ASSEM_, there is no segfault. >> Tremor without fastermdct.patch also doesn't have this problem. >> >> I tried debugging the code for a moment, but this code (MDCT + >> #defines + lots of >> assmebly) is completely incomprehensible to me. >> >> Unfortunately, I don't have gdb built for this platform (I managed to find the >> problematic line with `fprintf(stderr, ...)`, which itself could change the way >> it segfaults). At first sight all variables are initialized to proper values. >> >> The ARM processor I'm using is (according to /proc/cpuinfo): >> >> Processor : ARMv6-compatible processor rev 4 (v6l) >> CPU implementer : 0x41 >> CPU architecture: 6TEJ >> CPU variant : 0x0 >> CPU part : 0xb36 >> CPU revision : 4 >> Hardware : Freescale MX31/MX32 3-Stack Board >> >> >> Can you help me handle this issue? >> >> -- >> regards, >> Slawomir Testowy > > > The android has the same problem (after enabling ASM optimzations), > crash/segfault immediately when trying to play a song. There's a number > of codecs that do not work and most (or all, I don't know exactly) of > them use the mdct: wma, vorbis, aac, a52, cook. I strongly suspect it's > the very same problem, since IIUC the NDKs gcc has -fPIC on by default > (as does the android gcc target in gcc 4.6). > > I hope this can be resolved. > > Best regards. Received on 2010-10-10 Page template was last modified "Tue Sep 7 00:00:02 2021" The Rockbox Crew -- Privacy Policy |