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| Overall, by ARMv8.0, a new feature was added to the processor. In this section, the primary focus is on endianness, and the feature named “FEAT_MixedEnd” from ARMv8 processors allows programmers to control the endianness of the memory. This means that the ARMv8 have implemented both little-endian and big-endian. Note that the feature “FEAT_MixedEnd” is optional. Not all processor manufacturers implement this feature, but it can be verified. To find out the presence of the “FEAT_MixedEnd” feature, the ID_AA64MMFR0_EL1 register’s BigEnd bit field must be checked. If the feature “FEAT_MixedEnd” is implemented, | Overall, by ARMv8.0, a new feature was added to the processor. In this section, the primary focus is on endianness, and the feature named “FEAT_MixedEnd” from ARMv8 processors allows programmers to control the endianness of the memory. This means that the ARMv8 have implemented both little-endian and big-endian. Note that the feature “FEAT_MixedEnd” is optional. Not all processor manufacturers implement this feature, but it can be verified. To find out the presence of the “FEAT_MixedEnd” feature, the ID_AA64MMFR0_EL1 register’s BigEnd bit field must be checked. If the feature “FEAT_MixedEnd” is implemented, | ||
| - | On the Raspberry Pi 5 running AArch64, the higher exception layers control the endianness of the lower exception layers. For example, the code running in the Exception Level EL1 layer can control the endianness of the EL0 Exception Level. Note that if the Linux OS is already running on the Raspberry PI, the kernel EL1 endianness should not be changed, because the OS runs at the EL1 layer and no OS can switch endianness at runtime (at the moment). | + | On the Raspberry Pi 5 running AArch64, the higher exception layers control the endianness of the lower exception layers. For example, the code running in the Exception Level EL1 layer can control the endianness of the EL0 Exception Level. Note that if the Linux-based |
| As both modes are supported in ARMv8, it may be necessary to determine the EL0 endianness settings. The CPU's registers hold all the information about the current CPU endianness. Similar to the selected CPU, the ID_AA64MMFR0_EL1 register is an AArch64 Memory Model Feature register that stores endianness information. | As both modes are supported in ARMv8, it may be necessary to determine the EL0 endianness settings. The CPU's registers hold all the information about the current CPU endianness. Similar to the selected CPU, the ID_AA64MMFR0_EL1 register is an AArch64 Memory Model Feature register that stores endianness information. | ||
