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Docs: RISC-V Update rv64* BSPs to medany and 0x80000000 start address

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Closes #4775
This commit is contained in:
Hesham Almatary 2022-12-18 14:30:15 +00:00
parent a3d7dd1b88
commit 6794f0166c
1 changed files with 12 additions and 15 deletions
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27
user/bsps/bsps-riscv.rst
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@ -8,7 +8,7 @@ riscv (RISC-V)
riscv
=====
This BSP offers 15 variants:
This BSP offers 12 variants:
* rv32i
@ -26,22 +26,20 @@ This BSP offers 15 variants:
* rv64imac
* rv64imac_medany
* rv64imafd
* rv64imafd_medany
* rv64imafdc
* rv64imafdc_medany
* frdme310arty
* mpfs64imafdc
Each variant corresponds to a GCC multilib. A particular variant reflects an
ISA with ABI and code model choice.
Each rv* variant corresponds to a GCC multilib. A particular variant reflects an
ISA with ABI and code model choice. All rv64 BSPs have medany code model by
default, while rv32 BSPs are medlow. The reason is that RV32 medlow can access
the entire 32-bit address space, while RV64 medlow can only access addresses
below 0x80000000. With RV64 medany, it's possible to perform accesses above
0x80000000.
The BSP must be started im machine mode.
@ -94,8 +92,7 @@ configuration INI file. The ``waf`` defaults can be used to inspect the values.
by default).
``RISCV_RAM_REGION_BEGIN``
The begin of the RAM region for linker command file (default is 0x70000000
for 64-bit with -mcmodel=medlow and 0x80000000 for all other).
The begin of the RAM region for linker command file (default is 0x80000000).
``RISCV_RAM_REGION_SIZE``
The size of the RAM region for linker command file (default 64MiB).
@ -145,13 +142,13 @@ QEMU
----
All of the BSP variants that start with rv can be run on QEMU's virt machine.
For instance, to run the ``rv64imafdc_medany`` BSP with the following
"config.ini" file:
For instance, to run the ``rv64imafdc`` BSP with the following
"config.ini" file.
.. code-block:: none
[riscv/rv64imafdc_medany]
[riscv/rv64imafdc]
Run the following QEMU command:
Run the following QEMU command.
.. code-block:: shell
$ qemu-system-riscv64 -M virt -nographic -bios $RTEMS_EXE