My VM's can't seem to be untied from actual physical memory....
I've got a nice old moldy version of sel4, around version 8 I think, but
it's got some life left if we can figure out how to remap our VMs to 0
instead of mapping virtual directly equal physical... In other words, for
some reason, we map virtual == physical, and have to tell the VM that it is
up at some high-level address. We would like to be able to pick a physical
patch of memory, and map it to zero in the VM, so the VM can believe it is
at 0. Honestly I don't understand why that isn't the default anyway... But
I've found examples where I can specify a physical address and get back an
arbitrary virtual address, and other examples where I can specify a virtual
address and get back an arbitrary physical page. What I need, is a way to
specify both the physical and the virtual addresses into my VM vspace.
Would you happen to have an example or two on hand?
For a little more context, I've got the following code, which appears to
map the first page ok, but then fails trying to map the next page when
called a second time:
map_ram_to(vspace_t *vspace, vspace_t *vmm_vspace, vka_t* vka, uintptr_t
paddr, uintptr_t vaddr)
{
vka_object_t frame_obj;
cspacepath_t frame[2];
reservation_t res;
int err;
/* reserve vspace */
printf("map_ram_to, reserve phys mem at %p to vaddr %p\n", (void
*)paddr, (void *)vaddr);
res = vspace_reserve_range_at(vspace, (void *)paddr, 0x1000,
seL4_AllRights, 1);
if (!res.res) {
ZF_LOGF("Failed to reserve range");
return NULL;
}
/* map phys addr ro frame obj */
printf("map_ram_to, alloc phys mem at %p\n", (void *)paddr);
err = vka_alloc_frame_at(vka, 12, paddr, &frame_obj);
if (err) {
printf("ERROR VKA alloc ptr: %p\n", vka->data);
ZF_LOGF("Failed vka_alloc_frame_maybe_device in devices.c");
vspace_free_reservation(vspace, res);
return NULL;
}
vka_cspace_make_path(vka, frame_obj.cptr, &frame[0]);
printf("map_ram vka_cspace_alloc_path\n");
err = vka_cspace_alloc_path(vka, &frame[1]);
if (err) {
ZF_LOGF("Failed vka_cspace_alloc_path");
vka_free_object(vka, &frame_obj);
vspace_free_reservation(vspace, res);
return NULL;
}
printf("map_ram vka_cnode_copy\n");
err = vka_cnode_copy(&frame[1], &frame[0], seL4_AllRights);
if (err) {
ZF_LOGF("Failed vka_cnode_copy");
vka_cspace_free(vka, frame[1].capPtr);
vka_free_object(vka, &frame_obj);
vspace_free_reservation(vspace, res);
return NULL;
}
err = map_page(vspace, frame_obj.cptr, (void *)vaddr, seL4_AllRights,
1, 12);
vspace_free_reservation(vspace, res);
if (err) {
printf("FAILED Failed vspace_map_pages_at_vaddr\n");
vka_cspace_free(vka, frame[1].capPtr);
vka_free_object(vka, &frame_obj);
return NULL;
}
printf("map_ram_to, worked and zeroed at %p\n", (void *)paddr);
return (void *)paddr;
}
Help is greatly appreciated!
Richard H. Clark
