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