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| en:multiasm:paarm:chapter_5_3 [2026/02/27 15:46] – jtokarz | en:multiasm:paarm:chapter_5_3 [2026/02/27 16:04] (current) – jtokarz | ||
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| ARMv8 has an additional 32 register set for floating-point and vector operations, like general-purpose registers. These registers are 128 bits wide and, like general-purpose registers, can be accessed in several ways. The letters for these registers identify byte (Bx), half-word (Hx), single-word (Sx), double-word (Dx) and quad-word (Qx) access. | ARMv8 has an additional 32 register set for floating-point and vector operations, like general-purpose registers. These registers are 128 bits wide and, like general-purpose registers, can be accessed in several ways. The letters for these registers identify byte (Bx), half-word (Hx), single-word (Sx), double-word (Dx) and quad-word (Qx) access. | ||
| - | {{ : | + | <figure vectorreg> |
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| - | {{ : | + | {{ : |
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| - | More information on these registers and operations performed with floating-point is described in the following section, “Advanced Assembly Programming”. | + | More information on these registers and operations performed with floating-point is described in the following section: [[en: |
| ===== CPU Configuration===== | ===== CPU Configuration===== | ||
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| ''< | ''< | ||
| - | {{ : | + | <figure exceptionlevels> |
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| - | In the image, all of the exception levels are visualised. The Orange area is so-called the untrusted or non-secure state. The region with a blue background is the Operating System and its parts and applications. User applications can request resources using SVC (supervisor calls), or on Raspberry Pi OS (and others), this is called SysCalls. The operating system is treated as a separate program on the exception level EL1 from the EL2 perspective. If the hypervisor is available, the OS may request resources via HVC (Hypervisor calls), and the hypervisor can request resources from the secure monitor via SMC (Secure monitor calls). On Raspberry Pi 5, the bootloader runs on EL3, loading memory and initialising the hardware. Then the operating system is started at the EL1 level, and the rest of the applications in the OS are at the EL0 level. Raspberry Pi 5 does not have hypervisor software, which is why Exception Level 2 is not used. | + | In Fig. {{ref> |
| The Green region is a Secure State where only special secure applications and operating systems are executed. This may be used in system duplication, | The Green region is a Secure State where only special secure applications and operating systems are executed. This may be used in system duplication, | ||
