Re: V4L2: __ucmpdi2 undefined on ppc
From: Stephane Marchesin <hidden>
Date: 2008-02-06 14:39:54
On 12/17/06, David Woodhouse [off-list ref] wrote:
You still get to 'accidentally' do 64-bit arithmetic in-kernel that way though. Might be better just to provide __ucmpdi2, just as we have for the other functions which are required from libgcc It'd be better just to fix the compiler though -- which is in fact what they've done: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=25724 http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21237 I've applied this as a temporary hack to the Fedora kernel until the compiler is updated there...
Hello, We're hitting this i nouveau as well (http://nouveau.freedesktop.org), since we make extensive use ot 64 bit ints. Over time, we've had a number of reports on this issue, and at one point I read that it should be fixed in gcc. But recently, a nouveau user on PPC32 (Henrik in CC:) reported the issue again with gcc 4.2.3. Others have it on gcc 4.2.2 too: http://bugs.freedesktop.org/show_bug.cgi?id=10547 So, the point of this email is to ask about the possibility of merging in one of the __ucmpdi2 patches, like David's which is kept below for reference. Most distros seem to ship with such a patch already, and it seems that other drivers hit this as well. Thanks, Stephane
quoted hunk ↗ jump to hunk
--- linux-2.6.19.ppc/arch/powerpc/kernel/misc_32.S~ 2006-11-29 21:57:37.000000000 +0000 +++ linux-2.6.19.ppc/arch/powerpc/kernel/misc_32.S 2006-12-17 12:19:48.000000000 +0000@@ -728,6 +728,27 @@ _GLOBAL(__lshrdi3) or r4,r4,r7 # LSW |= t2 blr +/* + * __ucmpdi2: 64-bit comparison + * + * R3/R4 has 64 bit value A + * R5/R6 has 64 bit value B + * result in R3: 0 for A < B + * 1 for A == B + * 2 for A > B + */ +_GLOBAL(__ucmpdi2) + cmplw r7,r3,r5 # compare high words + li r3,0 + blt r7,2f # a < b ... return 0 + bgt r7,1f # a > b ... return 2 + cmplw r6,r4,r6 # compare low words + blt r6,2f # a < b ... return 0 + li r3,1 + ble r6,2f # a = b ... return 1 +1: li r3,2 +2: blr + _GLOBAL(abs) srawi r4,r3,31 xor r3,r3,r4 --- linux-2.6.19.ppc/arch/powerpc/kernel/ppc_ksyms.c~ 2006-12-15 17:19:56.000000000 +0000 +++ linux-2.6.19.ppc/arch/powerpc/kernel/ppc_ksyms.c 2006-12-17 12:16:54.000000000 +0000@@ -161,9 +161,11 @@ EXPORT_SYMBOL(to_tm); long long __ashrdi3(long long, int); long long __ashldi3(long long, int); long long __lshrdi3(long long, int); +int __ucmpdi2(uint64_t, uint64_t); EXPORT_SYMBOL(__ashrdi3); EXPORT_SYMBOL(__ashldi3); EXPORT_SYMBOL(__lshrdi3); +EXPORT_SYMBOL(__ucmpdi2); #endif EXPORT_SYMBOL(memcpy); --dwmw2