On Tue, 2005-05-24 14:29:44 +0200, Mateusz Berezecki <[email protected]> wrote: > u64 mconst = somebig64bitvalue; > u64 tmp = some32bitvalue; > u64 r = mconst / tmp; > > I encounter compilation error and gcc reporting __udivdi3 has not been > found! > After firing up cscope I found that this function has never(?) been > implemented for > x86 architecture. How is it possible that during compilation process of > some module > make system tries to link with nonexisting function? > > I've also found a do_div() and it was sufficent for my purposes but Im > still curious about > __udivdi3. Can someone explain this issue to me? In some cases, gcc decides that a given division is too complicated to do it in one assembler instruction. That's especially true for things that newer CPUs support but older lack. In these cases, gcc emits a function call instead of the actual division and normally, libgcc would provide these functions. However, it's each architecture's decision to link-in libgcc or not, because it can open another can of worms. Alternatively, you can implement these little functions on your own and put them somewhere in some library file. MfG, JBG -- Jan-Benedict Glaw [email protected] . +49-172-7608481 _ O _ "Eine Freie Meinung in einem Freien Kopf | Gegen Zensur | Gegen Krieg _ _ O fuer einen Freien Staat voll Freier Bürger" | im Internet! | im Irak! O O O ret = do_actions((curr | FREE_SPEECH) & ~(NEW_COPYRIGHT_LAW | DRM | TCPA));
Attachment:
signature.asc
Description: Digital signature
- References:
- __udivdi3 and linux kernel u64 division question [x86]
- From: Mateusz Berezecki <[email protected]>
- __udivdi3 and linux kernel u64 division question [x86]
- Prev by Date: [0/5] Improvements to the ieee80211 layer
- Next by Date: [1/5] ieee80211: cleanup
- Previous by thread: Re: __udivdi3 and linux kernel u64 division question [x86]
- Next by thread: [0/5] Improvements to the ieee80211 layer
- Index(es):
 |