| Message ID | 20211203202559.253726-1-l.stelmach@samsung.com |
|---|---|
| State | Changes Requested |
| Headers | show |
| Series | [1/1] arch/arm: Choose page size for AArch64 | expand |
Łukasz, All, On 2021-12-03 21:25 +0100, Łukasz Stelmach spake thusly: > MMUs on AArch64 support three different page sizes: 4 kB, 16 kB, > and 64 kB. It is OS kernel's task to choose the configuration during > boot. Linux kernel can be compiled to support different page size. > To run on a system with pages larger than 4 kB userland binaries need > to be properly aligned during the linking process. However, binaries > prepared for systems with larger pages can run on systems with smaller > pages. > > Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> > --- > arch/Config.in.arm | 24 ++++++++++++++++++++++++ > arch/arch.mk.arm | 12 ++++++++++++ > 2 files changed, 36 insertions(+) > create mode 100644 arch/arch.mk.arm > > diff --git a/arch/Config.in.arm b/arch/Config.in.arm > index 4c0910e4f8..bc6452878d 100644 > --- a/arch/Config.in.arm > +++ b/arch/Config.in.arm > @@ -930,5 +930,29 @@ config BR2_READELF_ARCH_NAME > default "ARM" if BR2_arm || BR2_armeb > default "AArch64" if BR2_aarch64 || BR2_aarch64_be > > +choice > + prompt "Aarch64 MMU Page Size" > + default BR2_ARM_PAGE_SIZE_4K > + depends on BR2_aarch64 || BR2_aarch64_be > + help > + Choose MMU page size > + > +config BR2_ARM_PAGE_SIZE_4K > + bool "4KB" > + > +config BR2_ARM_PAGE_SIZE_16K > + bool "16KB" > + > +config BR2_ARM_PAGE_SIZE_64K > + bool "64KB" > + > +endchoice So, we alrady have a very similar choice for the ARC architecture, except it's for 4Ki, 8Ki, or 16Ki pages. I wonder if we could not make that choice more architecture-agnostic, and add the entries needed for Aarch64. Then arch would tell if their page size is configurable, and which sizes they support. For example: * arch/Config.in: config BR2_arcle # Ditto for arceb bool "arcle" select BR2_ARCH_HAS_MMU_PAGE_SIZE_4K if !BR2_arc750d select BR2_ARCH_HAS_MMU_PAGE_SIZE_8K select BR2_ARCH_HAS_MMU_PAGE_SIZE_16K if !BR2_arc750d config BR2_aarch64 # Ditto for BR2_aarch64_be bool "Aarch64" select BR2_ARCH_HAS_MMU_PAGE_SIZE_4K select BR2_ARCH_HAS_MMU_PAGE_SIZE_16K select BR2_ARCH_HAS_MMU_PAGE_SIZE_64K config BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE bool config BR2_ARCH_HAS_MMU_PAGE_SIZE_4K bool select BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE config BR2_ARCH_HAS_MMU_PAGE_SIZE_8K bool select BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE config BR2_ARCH_HAS_MMU_PAGE_SIZE_16K bool select BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE config BR2_ARCH_HAS_MMU_PAGE_SIZE_64K bool select BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE choice bool "MMU page size" depends on BR2_ARCH_HAS_CONFIGURABLE_MMU_PAGE_SIZE config BR2_ARCH_PAGE_SIZE_4K bool "4Ki" depends on BR2_ARCH_HAS_MMU_PAGE_SIZE_4K config BR2_ARCH_PAGE_SIZE_8K bool "8Ki" depends on BR2_ARCH_HAS_MMU_PAGE_SIZE_8K config BR2_ARCH_PAGE_SIZE_16K bool "16Ki" depends on BR2_ARCH_HAS_MMU_PAGE_SIZE_16K # No 32Ki entry because noone uses it. Yet. config BR2_ARCH_PAGE_SIZE_64K bool "64Ki" depends on BR2_ARCH_HAS_MMU_PAGE_SIZE_64K endchoice * toolchain-wrapper.mk # Explicitly set LD's "max-page-size" instead of relying on some defaults ifeq ($(BR2_ARCH_PAGE_SIZE_4K),y) ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=4096 else ifeq ($(BR2_ARCH_PAGE_SIZE_8K),y) ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=8192 else ifeq ($(BR2_ARCH_PAGE_SIZE_16K),y) ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=32768 else ifeq ($(BR2_ARCH_PAGE_SIZE_64K),y) ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=65536 And the corresponding code dropped from arch/Config.in.arc and arch/arch.mk.arc, and a bit of legacy handling to keep existing configurations functional. Otherwise, I don't see why that could not be a generic setting. Regards, Yann E. MORIN. > +config BR2_ARM_PAGE_SIZE > + string > + default "4K" if BR2_ARM_PAGE_SIZE_4K > + default "16K" if BR2_ARM_PAGE_SIZE_16K > + default "64K" if BR2_ARM_PAGE_SIZE_64K > + > # vim: ft=kconfig > # -*- mode:kconfig; -*- > diff --git a/arch/arch.mk.arm b/arch/arch.mk.arm > new file mode 100644 > index 0000000000..ef65c60f6c > --- /dev/null > +++ b/arch/arch.mk.arm > @@ -0,0 +1,12 @@ > +ifeq ($(filter y, $(BR2_aarch64) $(BR2_aarch64_be)), y) > + > +# Explicitly set LD's "max-page-size" instead of relying on some defaults > +ifeq ($(BR2_ARM_PAGE_SIZE_4K),y) > +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=4096 > +else ifeq ($(BR2_ARM_PAGE_SIZE_16K),y) > +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=32768 > +else ifeq ($(BR2_ARM_PAGE_SIZE_64K),y) > +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=65536 > +endif > + > +endif > -- > 2.30.2 > > _______________________________________________ > buildroot mailing list > buildroot@buildroot.org > https://lists.buildroot.org/mailman/listinfo/buildroot
diff --git a/arch/Config.in.arm b/arch/Config.in.arm index 4c0910e4f8..bc6452878d 100644 --- a/arch/Config.in.arm +++ b/arch/Config.in.arm @@ -930,5 +930,29 @@ config BR2_READELF_ARCH_NAME default "ARM" if BR2_arm || BR2_armeb default "AArch64" if BR2_aarch64 || BR2_aarch64_be +choice + prompt "Aarch64 MMU Page Size" + default BR2_ARM_PAGE_SIZE_4K + depends on BR2_aarch64 || BR2_aarch64_be + help + Choose MMU page size + +config BR2_ARM_PAGE_SIZE_4K + bool "4KB" + +config BR2_ARM_PAGE_SIZE_16K + bool "16KB" + +config BR2_ARM_PAGE_SIZE_64K + bool "64KB" + +endchoice + +config BR2_ARM_PAGE_SIZE + string + default "4K" if BR2_ARM_PAGE_SIZE_4K + default "16K" if BR2_ARM_PAGE_SIZE_16K + default "64K" if BR2_ARM_PAGE_SIZE_64K + # vim: ft=kconfig # -*- mode:kconfig; -*- diff --git a/arch/arch.mk.arm b/arch/arch.mk.arm new file mode 100644 index 0000000000..ef65c60f6c --- /dev/null +++ b/arch/arch.mk.arm @@ -0,0 +1,12 @@ +ifeq ($(filter y, $(BR2_aarch64) $(BR2_aarch64_be)), y) + +# Explicitly set LD's "max-page-size" instead of relying on some defaults +ifeq ($(BR2_ARM_PAGE_SIZE_4K),y) +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=4096 +else ifeq ($(BR2_ARM_PAGE_SIZE_16K),y) +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=32768 +else ifeq ($(BR2_ARM_PAGE_SIZE_64K),y) +ARCH_TOOLCHAIN_WRAPPER_OPTS += -Wl,-z,max-page-size=65536 +endif + +endif
MMUs on AArch64 support three different page sizes: 4 kB, 16 kB, and 64 kB. It is OS kernel's task to choose the configuration during boot. Linux kernel can be compiled to support different page size. To run on a system with pages larger than 4 kB userland binaries need to be properly aligned during the linking process. However, binaries prepared for systems with larger pages can run on systems with smaller pages. Signed-off-by: Łukasz Stelmach <l.stelmach@samsung.com> --- arch/Config.in.arm | 24 ++++++++++++++++++++++++ arch/arch.mk.arm | 12 ++++++++++++ 2 files changed, 36 insertions(+) create mode 100644 arch/arch.mk.arm