| Message ID | 20181030125553.5230-8-lukas.auer@aisec.fraunhofer.de |
|---|---|
| State | Superseded |
| Delegated to: | Andes |
| Headers | show |
| Series | General fixes / cleanup for RISC-V and improvements to qemu-riscv | expand |
Hi Lukas, On Tue, Oct 30, 2018 at 8:57 PM Lukas Auer <lukas.auer@aisec.fraunhofer.de> wrote: > > RISC-V has two code models, medium low (medlow) and medium any (medany). > Medlow limits addressable memory to a single 2 GiB range between the > absolute addresses -2 GiB and +2 GiB. Medany limits addressable memory > to any single 2 GiB address range. > By default, medlow is selected on 32-bit systems and medany on 64-bit > systems. This matches the configuration in Linux. > > The -mcmodel compiler flag is selected according to the Kconfig > configuration. > > Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> > --- > > Changes in v2: > - Change ISA string construction, as suggested by Bin Meng > > arch/riscv/Kconfig | 19 +++++++++++++++++++ > arch/riscv/Makefile | 9 ++++++++- > 2 files changed, 27 insertions(+), 1 deletion(-) > I had a further look at this, and I suspect we should stick to medlow for U-Boot, even for 64-bit. As U-Boot will be only running within the low 4GB memory space even for 64-bit. Adding medany seems unnecessary. Regards, Bin
Hi Bin, On Wed, 2018-10-31 at 10:13 +0800, Bin Meng wrote: > Hi Lukas, > > On Tue, Oct 30, 2018 at 8:57 PM Lukas Auer > <lukas.auer@aisec.fraunhofer.de> wrote: > > > > RISC-V has two code models, medium low (medlow) and medium any > > (medany). > > Medlow limits addressable memory to a single 2 GiB range between > > the > > absolute addresses -2 GiB and +2 GiB. Medany limits addressable > > memory > > to any single 2 GiB address range. > > By default, medlow is selected on 32-bit systems and medany on 64- > > bit > > systems. This matches the configuration in Linux. > > > > The -mcmodel compiler flag is selected according to the Kconfig > > configuration. > > > > Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> > > --- > > > > Changes in v2: > > - Change ISA string construction, as suggested by Bin Meng > > > > arch/riscv/Kconfig | 19 +++++++++++++++++++ > > arch/riscv/Makefile | 9 ++++++++- > > 2 files changed, 27 insertions(+), 1 deletion(-) > > > > I had a further look at this, and I suspect we should stick to medlow > for U-Boot, even for 64-bit. As U-Boot will be only running within > the > low 4GB memory space even for 64-bit. Adding medany seems > unnecessary. > > Regards, > Bin You are right, however I think it's actually because U-Boot is compiled as a position independent binary. U-Boot can be relocated above what's addressable with 32-bit if the memory is large enough. This should cause issues with medlow. I suspects that's the reason, but I am not entirely sure. What do you think? Thanks, Lukas
Hi Lukas, On Wed, Oct 31, 2018 at 11:01 PM Auer, Lukas <lukas.auer@aisec.fraunhofer.de> wrote: > > Hi Bin, > > On Wed, 2018-10-31 at 10:13 +0800, Bin Meng wrote: > > Hi Lukas, > > > > On Tue, Oct 30, 2018 at 8:57 PM Lukas Auer > > <lukas.auer@aisec.fraunhofer.de> wrote: > > > > > > RISC-V has two code models, medium low (medlow) and medium any > > > (medany). > > > Medlow limits addressable memory to a single 2 GiB range between > > > the > > > absolute addresses -2 GiB and +2 GiB. Medany limits addressable > > > memory > > > to any single 2 GiB address range. > > > By default, medlow is selected on 32-bit systems and medany on 64- > > > bit > > > systems. This matches the configuration in Linux. > > > > > > The -mcmodel compiler flag is selected according to the Kconfig > > > configuration. > > > > > > Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> > > > --- > > > > > > Changes in v2: > > > - Change ISA string construction, as suggested by Bin Meng > > > > > > arch/riscv/Kconfig | 19 +++++++++++++++++++ > > > arch/riscv/Makefile | 9 ++++++++- > > > 2 files changed, 27 insertions(+), 1 deletion(-) > > > > > > > I had a further look at this, and I suspect we should stick to medlow > > for U-Boot, even for 64-bit. As U-Boot will be only running within > > the > > low 4GB memory space even for 64-bit. Adding medany seems > > unnecessary. > > > > Regards, > > Bin > > You are right, however I think it's actually because U-Boot is compiled > as a position independent binary. U-Boot can be relocated above what's > addressable with 32-bit if the memory is large enough. This should > cause issues with medlow. > I suspects that's the reason, but I am not entirely sure. What do you > think? Sorry I missed this email. I just found in your v3 this patch was dropped. I think this is still needed to explicitly pass the code model to the compiler. I believe we only need change to: +choice + prompt "Code Model" + default CMODEL_MEDLOW I can include the modified patch in my upcoming series. Regards, Bin
Hi Bin, On Tue, 2018-11-13 at 15:34 +0800, Bin Meng wrote: > Hi Lukas, > > On Wed, Oct 31, 2018 at 11:01 PM Auer, Lukas > <lukas.auer@aisec.fraunhofer.de> wrote: > > > > Hi Bin, > > > > On Wed, 2018-10-31 at 10:13 +0800, Bin Meng wrote: > > > Hi Lukas, > > > > > > On Tue, Oct 30, 2018 at 8:57 PM Lukas Auer > > > <lukas.auer@aisec.fraunhofer.de> wrote: > > > > > > > > RISC-V has two code models, medium low (medlow) and medium any > > > > (medany). > > > > Medlow limits addressable memory to a single 2 GiB range > > > > between > > > > the > > > > absolute addresses -2 GiB and +2 GiB. Medany limits addressable > > > > memory > > > > to any single 2 GiB address range. > > > > By default, medlow is selected on 32-bit systems and medany on > > > > 64- > > > > bit > > > > systems. This matches the configuration in Linux. > > > > > > > > The -mcmodel compiler flag is selected according to the Kconfig > > > > configuration. > > > > > > > > Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> > > > > --- > > > > > > > > Changes in v2: > > > > - Change ISA string construction, as suggested by Bin Meng > > > > > > > > arch/riscv/Kconfig | 19 +++++++++++++++++++ > > > > arch/riscv/Makefile | 9 ++++++++- > > > > 2 files changed, 27 insertions(+), 1 deletion(-) > > > > > > > > > > I had a further look at this, and I suspect we should stick to > > > medlow > > > for U-Boot, even for 64-bit. As U-Boot will be only running > > > within > > > the > > > low 4GB memory space even for 64-bit. Adding medany seems > > > unnecessary. > > > > > > Regards, > > > Bin > > > > You are right, however I think it's actually because U-Boot is > > compiled > > as a position independent binary. U-Boot can be relocated above > > what's > > addressable with 32-bit if the memory is large enough. This should > > cause issues with medlow. > > I suspects that's the reason, but I am not entirely sure. What do > > you > > think? > > Sorry I missed this email. I just found in your v3 this patch was > dropped. I think this is still needed to explicitly pass the code > model to the compiler. I believe we only need change to: > > +choice > + prompt "Code Model" > + default CMODEL_MEDLOW > > I can include the modified patch in my upcoming series. > > Regards, > Bin Ok, I miss-understood that. Sounds good, thanks! Lukas
diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig index 0de77a75d7..371921b412 100644 --- a/arch/riscv/Kconfig +++ b/arch/riscv/Kconfig @@ -38,6 +38,25 @@ config ARCH_RV64I endchoice +choice + prompt "Code Model" + default CMODEL_MEDLOW if 32BIT + default CMODEL_MEDANY if 64BIT + +config CMODEL_MEDLOW + bool "medium low code model" + help + U-Boot and its statically defined symbols must lie within a single 2 GiB + address range and must lie between absolute addresses -2 GiB and +2 GiB. + +config CMODEL_MEDANY + bool "medium any code model" + help + U-Boot and its statically defined symbols must be within any single 2 GiB + address range. + +endchoice + config RISCV_ISA_C bool "Emit compressed instructions" default y diff --git a/arch/riscv/Makefile b/arch/riscv/Makefile index 55d7c6550e..0b80eb8d86 100644 --- a/arch/riscv/Makefile +++ b/arch/riscv/Makefile @@ -17,8 +17,15 @@ endif ifeq ($(CONFIG_RISCV_ISA_C),y) ARCH_C = c endif +ifeq ($(CONFIG_CMODEL_MEDLOW),y) + CMODEL = medlow +endif +ifeq ($(CONFIG_CMODEL_MEDANY),y) + CMODEL = medany +endif -ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) +ARCH_FLAGS = -march=$(ARCH_BASE)$(ARCH_A)$(ARCH_C) -mabi=$(ABI) \ + -mcmodel=$(CMODEL) PLATFORM_CPPFLAGS += $(ARCH_FLAGS) CFLAGS_EFI += $(ARCH_FLAGS)
RISC-V has two code models, medium low (medlow) and medium any (medany). Medlow limits addressable memory to a single 2 GiB range between the absolute addresses -2 GiB and +2 GiB. Medany limits addressable memory to any single 2 GiB address range. By default, medlow is selected on 32-bit systems and medany on 64-bit systems. This matches the configuration in Linux. The -mcmodel compiler flag is selected according to the Kconfig configuration. Signed-off-by: Lukas Auer <lukas.auer@aisec.fraunhofer.de> --- Changes in v2: - Change ISA string construction, as suggested by Bin Meng arch/riscv/Kconfig | 19 +++++++++++++++++++ arch/riscv/Makefile | 9 ++++++++- 2 files changed, 27 insertions(+), 1 deletion(-)