Imbus/xv6-riscv-kernel
1
Fork 0
Code Issues Pull requests Projects Releases Packages Wiki Activity Actions

One way of supporting a guard page below kstack: allocate kstacks in

Browse source 
procinit() and map them high up (below TRAMPOLNE) with an empty
mapping below each stack.  Never free a kernel stack.

Another way would be to allocate and map them dynamically, but then we
need to reload page table when switching processes in scheduler()
and/or have a kernel pagetable per proc (if we want k->stack to be the
same virtual address in each process).

One gotcha: kernel addresses are not equal to physical addresses for
stack addresses.  A stack address must be translated if we need its
physical address (e.g., virtio passes a stack address to the disk).
This commit is contained in:
Frans Kaashoek 2019-07-19 08:38:51 -04:00
parent b924e44f06
commit 9156632701
5 changed files with 42 additions and 14 deletions
Download patch file Download diff file Expand all files Collapse all files

2
kernel/virtio_disk.c
View file

@ -199,7 +199,7 @@ virtio_disk_rw(struct buf *b)
buf0.reserved = 0;
buf0.sector = sector;
desc[idx[0]].addr = (uint64) &buf0;
desc[idx[0]].addr = (uint64) kernelpa((uint64) &buf0);
desc[idx[0]].len = sizeof(buf0);
desc[idx[0]].flags = VRING_DESC_F_NEXT;
desc[idx[0]].next = idx[1];