On 5/28/24 4:54 PM, benja...@sipsolutions.net wrote: [...] > diff --git a/arch/um/Kconfig b/arch/um/Kconfig > index 93a5a8999b07..5d111fc8ccb7 100644 > --- a/arch/um/Kconfig > +++ b/arch/um/Kconfig > @@ -208,6 +208,7 @@ config MMAPPER > > config PGTABLE_LEVELS > int > + default 4 if 4_LEVEL_PGTABLES > default 3 if 3_LEVEL_PGTABLES > default 2 > [...] > diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig > index 186f13268401..72dc7b0b3a33 100644 > --- a/arch/x86/um/Kconfig > +++ b/arch/x86/um/Kconfig > @@ -28,16 +28,34 @@ config X86_64 > def_bool 64BIT > select MODULES_USE_ELF_RELA > > -config 3_LEVEL_PGTABLES > - bool "Three-level pagetables" if !64BIT > - default 64BIT > - help > - Three-level pagetables will let UML have more than 4G of physical > - memory. All the memory that can't be mapped directly will be treated > - as high memory. > - > - However, this it experimental on 32-bit architectures, so if unsure > say > - N (on x86-64 it's automatically enabled, instead, as it's safe there). > +choice > + prompt "Pagetable levels" if EXPERT > + default 2_LEVEL_PGTABLES if !64BIT > + default 4_LEVEL_PGTABLES if 64BIT > + > + config 2_LEVEL_PGTABLES > + bool "Three-level pagetables" if !64BIT
Nit: s/Three-level/Two-level/ > + depends on !64BIT > + help > + Two-level page table for 32-bit architectures. > + > + config 3_LEVEL_PGTABLES > + bool "Three-level pagetables" if 64BIT > + help > + Three-level pagetables will let UML have more than 4G of > physical > + memory. All the memory that can't be mapped directly will be > treated > + as high memory. > + > + However, this it experimental on 32-bit architectures, so if > unsure say > + N (on x86-64 it's automatically enabled, instead, as it's > safe there). > + > + config 4_LEVEL_PGTABLES > + bool "Four-level pagetables" if 64BIT > + depends on 64BIT > + help > + Four-level pagetables, gives a bigger address space which can > be > + useful for some applications (e.g. ASAN). On 64bit, it appears that 4_LEVEL_PGTABLES won't be selected by running "make ARCH=um defconfig", and PGTABLE_LEVELS will be 2. I got the following search result in "make ARCH=um menuconfig": │ Symbol: 4_LEVEL_PGTABLES [=n] │ Type : bool │ Defined at arch/x86/um/Kconfig:51 │ Prompt: Four-level pagetables │ Depends on: <choice> && 64BIT [=y] │ Location: │ (1) -> UML-specific options │ -> Pagetable levels (<choice> [=n]) │ -> Four-level pagetables (4_LEVEL_PGTABLES [=n]) And 4_LEVEL_PGTABLES will be selected if I turn on EXPERT manually. Regards, Tiwei > +endchoice > > config ARCH_HAS_SC_SIGNALS > def_bool !64BIT
