These functions are those that need be implemented by backing
store outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
These functions and data structures are those that need
to be implemented by eviction algorithm and application
outside kernel. Promote them from z_* so these can be
included in documentation.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
Add a 'U' suffix to values when computing and comparing against
unsigned variables and other related fixes of the same MISRA rule (10.4)
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
This adds a new kconfig CONFIG_SRAM_OFFSET to specify the offset
from beginning of SRAM where the kernel begins. On x86 and
PC compatible platforms, the first 1MB of RAM is reserved and
Zephyr should not link anything there. However, this 1MB still
needs to be mapped by the MMU to access various platform related
information. CONFIG_SRAM_OFFSET serves similar function as
CONFIG_KERNEL_VM_OFFSET and is needed for proper phys/virt
address translations.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The Z_BOOT_VIRT_TO_PHYS() and Z_BOOT_PHYS_TO_VIRT() address
translation macros are flipped in their calculations.
The calculation is supposed to be:
virt = phys + ((KERNEL_VM_BASE + KERNEL_VM_OFFSET) -
SRAM_BASE_ADDRESS)
So fix the them.
Signed-off-by: Daniel Leung <daniel.leung@intel.com>
The linker script defines `z_mapped_size` as follows:
```
z_mapped_size = z_mapped_end - z_mapped_start;
```
This is done with the belief that precomputed values at link time will
make the code smaller and faster.
On Aarch64, symbol values are relocated and loaded relative to the PC
as those are normally meant to be memory addresses.
Now if you have e.g. `CONFIG_SRAM_BASE_ADDRESS=0x2000000000` then
`z_mapped_size` might still have a reasonable value, say 0x59334.
But, when interpreted as an address, that's very very far from the PC
whose value is in the neighborhood of 0x2000000000. That overflows the
4GB relocation range:
```
kernel/libkernel.a(mmu.c.obj): in function `z_mem_manage_init':
kernel/mmu.c:527:(.text.z_mem_manage_init+0x1c):
relocation truncated to fit: R_AARCH64_ADR_PREL_PG_HI21
```
The solution is to define `Z_KERNEL_VIRT_SIZE` in terms of
`z_mapped_end - z_mapped_start` at the source code level. Given this
is used within loops that already start with `z_mapped_start` anyway,
the compiler is smart enough to combine the two occurrences and
dispense with a size counter, making the code effectively
slightly better for all while avoiding the Aarch64 relocation
overflow:
```
text data bss dec hex filename
1216 8 294936 296160 484e0 mmu.c.obj.arm64.before
1212 8 294936 296156 484dc mmu.c.obj.arm64.after
1110 8 9244 10362 287a mmu.c.obj.x86-64.before
1106 8 9244 10358 2876 mmu.c.obj.x86-64.after
```
Signed-off-by: Nicolas Pitre <npitre@baylibre.com>
Some arches like x86 need all memory mapped so that they can
fetch information placed arbitrarily by firmware, like ACPI
tables.
Ensure that if this is the case, the kernel won't accidentally
clobber it by thinking the relevant virtual memory is unused.
Otherwise this has no effect on page frame management.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
If we evict enough pages to completely fill the backing store,
through APIs like k_mem_map(), z_page_frame_evict(), or
z_mem_page_out(), this will produce a crash the next time we
try to handle a page fault.
The backing store now always reserves a free storage location
for actual page faults.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
If we evict enough pages to completely fill the backing store,
through APIs like k_mem_map(), z_page_frame_evict(), or
z_mem_page_out(), this will produce a crash the next time we
try to handle a page fault.
The backing store now always reserves a free storage location
for actual page faults.
Signed-off-by: Andrew Boie <andrew.p.boie@intel.com>
