On Tue, May 28, 2019 at 6:50 PM Greentime Hu <greent...@andestech.com> wrote: > > Hi Bin, > On Tue, May 28, 2019 at 05:58:47PM +0800, Bin Meng wrote: > > Hi Greentime, > > > > On Tue, May 28, 2019 at 3:54 PM Greentime Hu <greent...@andestech.com> > > wrote: > > > > > > Hi Bin, > > > On Fri, May 24, 2019 at 05:40:08PM +0800, Bin Meng wrote: > > > > Hi Eric, > > > > > > > > On Fri, May 24, 2019 at 4:04 PM Eric Lin <dslin1...@gmail.com> wrote: > > > > > > > > > > Hi Bin > > > > > > > > > > Bin Meng <bmeng...@gmail.com> ??? 2019???5???22??? ?????? > > > > > ??????5:25????????? > > > > > > > > > > > > Hi Eric, > > > > > > > > > > > > On Wed, May 22, 2019 at 4:23 PM <tesh...@andestech.com> wrote: > > > > > > > > > > > > > > Hi Bin, > > > > > > > > > > > > > > > -----Original Message----- > > > > > > > > From: Bin Meng [mailto:bmeng...@gmail.com] > > > > > > > > Sent: Tuesday, May 21, 2019 3:56 PM > > > > > > > > To: Eric Te-Sheng Lin(?????????) > > > > > > > > Cc: U-Boot Mailing List; Lukas Auer; Anup Patel; Rick Jian-Zhi > > > > > > > > Chen(?????????); > > > > > > > > Greentime Ying-Han Hu(?????????); dslin1...@gmail.com > > > > > > > > Subject: Re: [PATCH] riscv: add Kconfig entries for the F and D > > > > > > > > ISA extensions > > > > > > > > support > > > > > > > > > > > > > > > > Hi Eric, > > > > > > > > > > > > > > > > On Tue, May 21, 2019 at 3:18 PM Eric Lin > > > > > > > > <tesh...@andestech.com> wrote: > > > > > > > > > > > > > > > > > > This patch add Kconfig entries for the F (Single-Precision) > > > > > > > > > > > > > > > > adds > > > > > > > > > > > > > > > > > > > > > > OK I'll correct it as adds > > > > > > > > > > > > > > > > and D (Double-Precision) floating point instruction-set > > > > > > > > > extensions. > > > > > > > > > > > > > > > > > > > > > > > > > Could you please provide reason that why U-Boot has to be > > > > > > > > compiled using F/D > > > > > > > > extension? > > > > > > > > > > > > > > > > > > > > > > Cause on AE350 platform, we have two different kinds of toolchain > > > > > > > v5d (support I/M/A/C/F/D ISA) and > > > > > > > v5 (support I/M/A/C ISA). If we use the v5d toolchain to build > > > > > > > U-Boot it will build fail, so we would like to add F/D extension > > > > > > > on U-Boot. > > > > > > > > > > > > I don't understand. What difference do these two toochains have? > > > > > > Isn't > > > > > > the v5d toolchain's default -march string be pre-configured to > > > > > > imafd? > > > > > > But even if the toolchain is pre-configured to generate fd > > > > > > instruction, I think it can be override by the compiler flags. Can > > > > > > you > > > > > > please share the details of the toolchain you used? I suspect you > > > > > > have > > > > > > to fix your toolchain, not U-Boot. > > > > > > > > > > > > > > > > It's seems the ABI issue. Because our toolchain don't support > > > > > multilib, the v5d toolchain libraries ABI is ilp64d. > > > > > If I use the v5d toolchain to build U-Boot with -mabi=lp64, it will > > > > > get link error as below: > > > > > > > > Then please fix your compiler. Passing -mabi=lp64 to compiler is > > > > definitely correct. > > > > > > One of our customer ever used floating point in their project. They want > > > to calculate something with floating point instructions in u-Boot before > > > entering kernel. > > > > This is a new use case. For other architectures like x86, we don't > > allow U-Boot to be compiled using hardware float ABI. Why can't they > > use software floating point instead? > > It's because they'd like to calculate something very quickly. It may just be > done in few cycles with floating point instructions and it will be very useful > for their usages instead of using soft-float. > > That's the reason they ask us to provide such kind of CONFIG and we think it > might also be helpful for users who are trying to do some mathematics with > floating point instructions in u-Boot. >
I will have to leave this to other people to comment. I personally do not like this to be supported in the upstream U-Boot. However if others do not object, I am OK too. Regards, Bin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot