When the .elf file is loaded from disk, the kernel must be given write
access to the allocated .text section in the task's address environment.
The access is removed after the elf is loaded and relocations are done.
NOTE:
The reason this works for the ARM implementation, is that the ARM MMU
can be configured to give write access for the privileged mode, but
revoke write access for the user mode.
Regardless, it would be smart to revoke write access even for the
kernel, when the kernel does not need it. This framework allows doing
that, if someone wishes to take up the task.
Summary:
- This commit adds support for semihosting and hostfs
Impact:
- None
Testing:
- Tested with nsh and nsh64 (defconfig will be updated later)
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>
Mappings are done with vaddr=paddr.
- I/O space mapped with two gigapages
- Kernel space mapped to statically allocated page tables. 2MB of kernel
memory is supported.
- Page pool is mapped to the kernel space, to allow virtual memory access
for the kernel e.g. to initialize the page memory when it is allocated.
by renaming riscv_dispatch_syscall to sys_callx, so the caller
don't need the immediate step(syscallx->riscv_dispatch_syscall)
Signed-off-by: Xiang Xiao <xiaoxiang@xiaomi.com>
Using the Kconfig macro does not work for RISC-V target, as there the
user heap follows .data/.bss and does not obey any Kconfig provided
boundary.
Added stubs for ARM and Z80 also.
Copy the kernel mappings to the new (user) address environment. The
copyuing is done exactly once. This relies on the fact that the kernel
L1/L2 mappings will never change, as all of the kernel memory is mapped
upon boot.
This implements initial support for kernel build (address environments,
page allocator) for RISC-V.
This is done a bit differently compared to the ARMV7 implementation:
- Support implemented for Sv39 MMU, however the implementation should be
extensible for other MMU types also.
- Instead of preserving and moving the L1 references around, a canonical
approach is used instead, where the page table base address register
is switched upon context switch.
- To preserve a bit of memory, only a single L1/L2 table is supported,
this gives access to 1GiB of virtual memory for each process, which
should be more than enough.
Some things worth noting:
- Assumes page pool is mapped with vaddr=paddr mappings
- The CONFIG_ARCH_XXXX_VBASE and CONFIG_ARCH_XXXX_NPAGES values are
ignored, with the exception of CONFIG_ARCH_DATA_VBASE which is used
for ARCH_DATA_RESERVE
- ARCH_DATA_RESERVE is placed at the beginning of the userspace task's
address environment
Summary:
- I noticed that maix-bit:smp does not work with QEMU.
- Actually, QEMU supports sifive_u (not K210) but it works
if FPU is disabled.
- This commit fixes this issue.
Impact:
- K210 with QEMU only
Testing:
- Tested with qemu-5.2
Signed-off-by: Masayuki Ishikawa <Masayuki.Ishikawa@jp.sony.com>
Selecting this option will pass "-Map=$(TOPDIR)$(DELIM)nuttx.map" to ld
when linking NuttX ELF. That file can be useful for verifying
and debugging magic section games, and for seeing which
pieces of code get eliminated with DEBUG_OPT_UNUSED_SECTIONS.
Signed-off-by: chao.an <anchao@xiaomi.com>
Enable this option to optimization the unused input sections with the
linker by compiling with " -ffunction-sections -fdata-sections ", and
linking with " --gc-sections ".
Signed-off-by: chao.an <anchao@xiaomi.com>
