Hi Ayan, On 25/04/2023 17:16, Ayan Kumar Halder wrote: > > On 24/04/2023 13:08, Michal Orzel wrote: >> Hi Ayan, > > Hi Michal, > > A clarification. > >> >> On 13/04/2023 19:37, Ayan Kumar Halder wrote: >>> >>> Some Arm based hardware platforms which does not support LPAE >>> (eg Cortex-R52), uses 32 bit physical addresses. >>> Also, users may choose to use 32 bits to represent physical addresses >>> for optimization. >>> >>> To support the above use cases, we have introduced arch independent >>> configs to choose if the physical address can be represented using >>> 32 bits (PHYS_ADDR_T_32) or 64 bits (!PHYS_ADDR_T_32). >>> For now only ARM_32 provides support to enable 32 bit physical >>> addressing. >>> >>> When PHYS_ADDR_T_32 is defined, PADDR_BITS is set to 32. >>> When PHYS_ADDR_T_32 is not defined for ARM_32, PADDR_BITS is set to 40. >>> When PHYS_ADDR_T_32 is not defined for ARM_64, PADDR_BITS is set to 48. >>> The last two are same as the current configuration used today on Xen. >>> >>> PADDR_BITS is also set to 48 when ARM_64 is defined. The reason being >>> the choice to select ARM_PA_BITS_32/ARM_PA_BITS_40/ARM_PA_BITS_48 is >>> currently allowed when ARM_32 is defined. >>> >>> Signed-off-by: Ayan Kumar Halder <[email protected]> >>> --- >>> Changes from - >>> v1 - 1. Extracted from "[XEN v1 8/9] xen/arm: Other adaptations required to >>> support 32bit paddr". >>> >>> v2 - 1. Introduced Kconfig choice. ARM_64 can select PHYS_ADDR_64 only >>> whereas >>> ARM_32 can select PHYS_ADDR_32 or PHYS_ADDR_64. >>> 2. For CONFIG_ARM_PA_32, paddr_t is defined as 'unsigned long'. >>> >>> v3 - 1. Allow user to define PADDR_BITS by selecting different config >>> options >>> ARM_PA_BITS_32, ARM_PA_BITS_40 and ARM_PA_BITS_48. >>> 2. Add the choice under "Architecture Features". >>> >>> v4 - 1. Removed PHYS_ADDR_T_64 as !PHYS_ADDR_T_32 means PHYS_ADDR_T_32. >>> >>> xen/arch/Kconfig | 3 +++ >>> xen/arch/arm/Kconfig | 37 ++++++++++++++++++++++++++-- >>> xen/arch/arm/include/asm/page-bits.h | 6 +---- >>> xen/arch/arm/include/asm/types.h | 6 +++++ >>> xen/arch/arm/mm.c | 5 ++++ >>> 5 files changed, 50 insertions(+), 7 deletions(-) >>> >>> diff --git a/xen/arch/Kconfig b/xen/arch/Kconfig >>> index 7028f7b74f..67ba38f32f 100644 >>> --- a/xen/arch/Kconfig >>> +++ b/xen/arch/Kconfig >>> @@ -1,6 +1,9 @@ >>> config 64BIT >>> bool >>> >>> +config PHYS_ADDR_T_32 >>> + bool >>> + >>> config NR_CPUS >>> int "Maximum number of CPUs" >>> range 1 4095 >>> diff --git a/xen/arch/arm/Kconfig b/xen/arch/arm/Kconfig >>> index 239d3aed3c..3f6e13e475 100644 >>> --- a/xen/arch/arm/Kconfig >>> +++ b/xen/arch/arm/Kconfig >>> @@ -19,13 +19,46 @@ config ARM >>> select HAS_PMAP >>> select IOMMU_FORCE_PT_SHARE >>> >>> +menu "Architecture Features" >>> + >>> +choice >>> + prompt "Physical address space size" if ARM_32 >> Why is it protected by ARM_32 but in the next line you add something >> protected by ARM_64? >> This basically means that for arm64, ARM_PA_BITS_XXX is never defined. > > Currently, I intentend to support 32-bit physical address configuration > for ARM_32 only. So in case of ARM_32, user will have a choice between > 32-bit and 40-bit PA. > > So, if it is ok with you, can I remove the below line and "config > ARM_PA_BITS_48 ..." ? I'm ok with that. I'm also ok to keep ARM_PA_BITS_48 but with ARM_32 protection removed to that the option makes sense. However, since there is no real choice for arm64, I think the former is better.
~Michal
