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Yann, Thanks for your detailed explanation! You are right I only need soft-float to be enabled so I would only need to compile the toolchain once. But I was not sure where to configure so that it will build with soft-float by default..Sorry for my newbe question. Could you elaborate a little bit on how to build with soft-float? I was using the original version of crosstool since I was not aware there is a new one now! On Sun, Mar 27, 2011 at 11:17 AM, Yann E. MORIN <yann.morin.1998@anciens.enib.fr> wrote: > Xun, All, > > On Sunday 27 March 2011 19:54:09 Xun Li wrote: >> I would need to use -msoft-float options to simulate floating point >> calculations, hence I would need multilib to be enabled in the cross >> compiler. > > You do not need multilib to enable soft-float. You can have the toolchain > be entirely soft-float by default. > > Multilib is needed if you want the _same_ toolchain to be able to emit > both HW and SW floating point operations. > > (Note: the compiler itself is able to generate both SW and HW, but the > libraries have to be compiled twice, once for each case). > >> How to do this in the crosstool? > > Do you mean crostool, as 'the original crosstool by Dan KEGEL' and > hosted there: http://kegel.com/crosstool/ ? > > Or do you mean crosstool-NG, as 'the fork by Yann E. MORIN" and > hosted there: http://ymorin.is-a-geek.org/projects/crosstool ? > > If the former, I don't really know. I think crosstool had support for > building multilb, but I never tried. > > For the latter, no, crostool-NG does not support multilib. Properly doing so > is not easy. Multilib has a broad meaning, depending on the architecture you > speak about. For example: > > - x86: > ?- 32-bit and 64bit, > ?- SW and HW floats > ?--> 4 combinations > > - ARM: > ?- SW and HW floats > ?- float format: VFP vs. softfp vs. NEON vs. Maverick > ? ? ? (not too sure I'm not speaking with my ass here...) > ?- armv4, armv5, armv6, armv7 > ?- big and little endian > ?- ARM vs. Thumb > ?- with or without interworking > ?- ARM vs. ARM26 ?(although ARM26 is really dead nowadays) > ?- OABI vs. EABI > ?--> a hell of a lot of combinations! (1024 if I count correctly?) > > MIPS: > ?- Pfff. I don't even want to try listing it... > ?--> a lot of conbinations as well (but less than for ARM?) > > And for each combination in said architecture, we'd need to build all of the > libraries running on the target. And even if you can do it, we'd need a way > to configure the subset of multilib we'd want. > > For now, I'd recommend to build one toolchain for each combination you need. > Basically, that boils down to two toolchain if you are only interested in HW > vs. SW floating point. > > Regards, > Yann E. MORIN. > > -- > .-----------------.--------------------.------------------.--------------------. > | ?Yann E. MORIN ?| Real-Time Embedded | /"\ ASCII RIBBON | Erics' conspiracy: | > | +33 662 376 056 | Software ?Designer | \ / CAMPAIGN ? ? | ?___ ? ? ? ? ? ? ? | > | +33 223 225 172 `------------.-------: ?X ?AGAINST ? ? ?| ?\e/ ?There is no ?| > | http://ymorin.is-a-geek.org/ | _/*\_ | / \ HTML MAIL ? ?| ? v ? conspiracy. ?| > '------------------------------^-------^------------------^--------------------' > -- Xun Li Computer Architecture Lab Department of Computer Science University of California, Santa Barbara -- For unsubscribe information see http://sourceware.org/lists.html#faq
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