Hi Bin, On Mon, 2018-10-22 at 15:21 +0800, Bin Meng wrote: > Hi Lukas, > > On Sat, Oct 20, 2018 at 6:09 AM Lukas Auer > <lukas.a...@aisec.fraunhofer.de> wrote: > > > > Add Kconfig entries for the C (compressed instructions) and A > > (atomic > > instructions) ISA extensions. Only the C ISA extension is > > selectable. > > This matches the configuration in Linux. > > > > The Kconfig entries are not used yet. A follow-up patch will select > > the > > appropriate compiler flags based on the Kconfig configuration. > > > > Signed-off-by: Lukas Auer <lukas.a...@aisec.fraunhofer.de> > > --- > > > > arch/riscv/Kconfig | 9 +++++++++ > > 1 file changed, 9 insertions(+) > > > > diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig > > index b81e0d990a..e15329c35e 100644 > > --- a/arch/riscv/Kconfig > > +++ b/arch/riscv/Kconfig > > @@ -38,6 +38,15 @@ config ARCH_RV64I > > > > endchoice > > > > +config RISCV_ISA_C > > + bool "Emit compressed instructions" > > + default y > > + help > > + This enables the compressed instructions ("C") ISA > > extension. > > This is a little bit confusing. Can we use Linux kernel's description > instead like below? > > Adds "C" to the ISA subsets that the toolchain is allowed > to emit > when building U-Boot, which results in compressed > instructions in the > U-Boot binary. >
Sure, I will change it in v2. > > + > > +config RISCV_ISA_A > > + def_bool y > > I do not believe U-Boot need to care about 'A' extension. So this can > be dropped? > That's right. The only reason it might be used in U-Boot is on multi- core systems. Linux chooses the hart to boot on with the hart lottery, which requires atomics. The first core to increment a flag wins and starts the boot process. We could do something similar in U-Boot, but I don't think it's necessary. In my patches (for the next patch series) I have added CONFIG_MAIN_HART to select the hart U-Boot should run on. I have included it here so that I can use it in the next patch to build the ISA string. I can remove it, but that would change the current behavior, which has atomics enabled. Thanks, Lukas > > + > > config 32BIT > > bool > > > > Regards, > Bin _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot