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risc-v/addrenv: Improve the commenting on struct arch_addrenv_s

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I can never remember whether the static page table list contains the
table's physical or kernel virtual address.. Add the fact as a comment
there.

Also add the limitations that come from this static page table approach
for Sv32.
This commit is contained in:
Ville Juven 2023-11-01 14:33:48 +02:00 committed by Xiang Xiao
parent 8a2d3958e9
commit aacdbf2a3b
1 changed files with 9 additions and 10 deletions
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19
arch/risc-v/include/arch.h
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@ -69,6 +69,11 @@
* *
* The implications ? They depend on the MMU type. * The implications ? They depend on the MMU type.
* *
* For Sv32 this means that:
* - A task can not have more than 4GB of memory allocated.
* - The minimum amount of memory needed for page tables per task is 8K,
* which gives access to 4MB of memory. This is plenty for many tasks.
*
* For Sv39 this means that: * For Sv39 this means that:
* - A task can not have more than 1GB of memory allocated. This should be * - A task can not have more than 1GB of memory allocated. This should be
* plenty enough... * plenty enough...
@ -78,26 +83,20 @@
struct arch_addrenv_s struct arch_addrenv_s
{ {
/* Pointers to MAX_LEVELS-1 tables here, one of each are allocated for the /* Physical addresses of the static page tables (levels N-1) here, these
* task when it is created. * are allocated when a task is created.
*/ */
uintptr_t spgtables[ARCH_SPGTS]; uintptr_t spgtables[ARCH_SPGTS];
/* For convenience store the text base here */ /* The text, data, heap bases and heap size here */
uintptr_t textvbase; uintptr_t textvbase;
/* For convenience store the data base here */
uintptr_t datavbase; uintptr_t datavbase;
/* For convenience store the heap base and initial size here */
uintptr_t heapvbase; uintptr_t heapvbase;
size_t heapsize; size_t heapsize;
/* For convenience store the satp value here */ /* The page directory root (satp) value */
uintptr_t satp; uintptr_t satp;
}; };