From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from digitaldans.com (digitaldans.com [69.36.177.99]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by ozlabs.org (Postfix) with ESMTPS id AFB922C0098 for ; Sat, 8 Jun 2013 11:13:51 +1000 (EST) Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 6.3 \(1503\)) Subject: Re: fsqrt From: Dan Malek In-Reply-To: <1370651667.3766.441.camel@pasglop> Date: Fri, 7 Jun 2013 18:13:43 -0700 Message-Id: <4A771AC5-37F2-4EC2-A733-52FFAAAB3C92@digitaldans.com> References: <1368679657.9603.32.camel@pasglop> <1368683156.9603.34.camel@pasglop> <6A3DF150A5B70D4F9B66A25E3F7C888D0701C307@039-SN2MPN1-012.039d.mgd.msft.net> <3E027F8168735B46AC006B1D0C7BB0020B1E040F@039-SN2MPN1-011.039d.mgd.msft.net> <1368684547.9603.38.camel@pasglop> <51947A00.9010504@windriver.com> <1368685307.9603.39.camel@pasglop> <51947E35.30808@windriver.com> <1368686426.9603.49.camel@pasglop> <5194800D.3010606@windriver.com> <6A3DF150A5B70D4F9B66A25E3F7C888D0701C498@039-SN2MPN1-012.039d.mgd.msft.net> <1368687133.9603.51.camel@pasglop> <1370577138.3766.342.camel@pasglop> <1370579976.3766.345.camel@pasglop> <3E027F8168735B46AC006B1D0C7BB0020B2135A0@039-SN2MPN1-012.039d.mgd.msft.net> <1370580426.3766.349.camel@pasglop> <3E027F8168735B46AC006B1D0C7BB0020B213817@039-SN2MPN1-012.039d.mgd.msft.net> <1370590884.3766.357.camel@pasglop> <3E027F8168735B46AC006B1D0C7BB0020B213A62@039-SN2MPN1-012.039d.mgd.msft.! ! net> <137 0595190.3766 .359.camel@pasglop> <1370595557.3766.362.camel@pasglop> <1370607245.3766.386.camel@pasglop> <1370647431.3766.432.camel@pasglop> <1370647524.3766.433.camel@pasglop> <1370647812.3766.436.camel@pasglop> <0CCB5C3E-E239-4269-B29C-93BF9D8201D6@digitaldans.com> <1370651667.3766.441.camel@pasglop> To: Benjamin Herrenschmidt Cc: Xie Shaohui-B21989 , Liu Qiang-B32616 , Zang Roy-R61911 , Timur Tabi , "tiejun.chen" , David Laight , Fleming Andy-AFLEMING , Bhushan Bharat-R65777 , linuxppc-dev@lists.ozlabs.org List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hi Ben. On Jun 7, 2013, at 5:34 PM, Benjamin Herrenschmidt = wrote: > The question is whether this is still relevant ? The only answer I could provide is that it's dependent upon the = libraries and how the distributions are built. It's also dependent upon = processors with hardware FP that don't implement all instructions in = hardware (who had that bright idea? :)) If distributions are fully all = soft-fp in user space or all hardware FP, it removes the one reason that = started the whole partial emulation option. > =85 And if the answer is > yes, There are multiple options, but I believe they are solved today. One is = the libraries coded with hardware load/store that are used by soft-fp, = another is hardware FP that doesn't implement all instructions in = hardware (which it seems is the basis of this thread, although I thought = was already solved). The variation here is that in the first case you = have to read/write user space soft-fp stack "registers," while in the = latter you read/write real FP registers. There used to be the third = variation where the stack was allocated and the emulation had to write = both places due to compiler function APIs or optimizations. Of course, = then there is the full-up kernel emulation where hardware is entirely = lacking. > =85 we still want that "minimum" emulation of load/stores/fmr as an > option, is there any reason why we can't replace the one in softemu8xx > with the existing (and unused) equivalent in do_mathemu ? It appears to me that 8xx custom code can be removed. I guess I should = try to boot it up, if anyone even cares these days. :) Thanks. -- Dan