Date: Mon, 1 Mar 2010 15:19:35 +0100 From: Giovanni Trematerra <giovanni.trematerra@gmail.com> To: Alexander Eichner <alexeichi@yahoo.de>, alc@freebsd.org Cc: freebsd-hackers@freebsd.org Subject: Re: Allocating physical memory without a kernel mapping Message-ID: <4e6cba831003010619j560f5b92n4c63ab2520cff7db@mail.gmail.com> In-Reply-To: <317657.30145.qm@web27603.mail.ukl.yahoo.com> References: <317657.30145.qm@web27603.mail.ukl.yahoo.com>
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On Mon, Mar 1, 2010 at 10:59 AM, Alexander Eichner <alexeichi@yahoo.de> wro=
te:
> Hi,
>
> I'm currently trying to finish the R0 memory implementation[1] of FreeBSD=
for VirtualBox. One of the missing methods allocates physical non contiguo=
us pages which don't need to have a kernel mapping (rtR0MemObjNativeAllocPh=
ysNC). I'm using vm_phys_alloc_contig to achieve this. The pages are than m=
apped into the user space VM process using pmap_enter (rtR0MemObjNativeMapU=
ser) and if they are not needed anymore vm_page_free_toq is used to free th=
e pages (rtR0MemObjNativeFree).
> Everything works as long as the VM runs but if the VM process terminates =
and I do something else the host will panic at some point (usually when I t=
ry to start a gnome session) with "pmap_enter: missing reference to page ta=
ble page <va>"[2].
> There seems to some problem with the wire count of that page but I can't =
see what I'm doing wrong at the moment.
> Thanks in advance for any help.
Please, try this patch against revision 26898.
--- memobj-r0drv-freebsd.c.orig 2010-02-26 10:28:44.000000000 +0100
+++ memobj-r0drv-freebsd.c 2010-02-26 13:55:35.000000000 +0100
@@ -209,8 +209,7 @@ int rtR0MemObjNativeAllocPage(PPRTR0MEMO
vm_page_t pPage;
pPage =3D vm_page_alloc(pMemFreeBSD->pObject, PageIndex,
- VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM |
- VM_ALLOC_WIRED);
+ VM_ALLOC_NOBUSY | VM_ALLOC_SYSTEM);
#if __FreeBSD_version >=3D 800000 /** @todo Find exact version number */
/* Fixes crashes during VM termination on
FreeBSD8-CURRENT amd64
@@ -220,9 +219,6 @@ int rtR0MemObjNativeAllocPage(PPRTR0MEMO
if (pPage)
{
- vm_page_lock_queues();
- vm_page_wire(pPage);
- vm_page_unlock_queues();
/* Put the page into the page table now. */
#if __FreeBSD_version >=3D 701105
pmap_enter(kernel_map->pmap, AddressDst,
VM_PROT_NONE, pPage,
@@ -253,6 +249,8 @@ int rtR0MemObjNativeAllocPage(PPRTR0MEMO
if (rc =3D=3D VINF_SUCCESS)
{
+ vm_map_wire(kernel_map, MapAddress,
MapAddress + cb,
+ VM_MAP_WIRE_SYSTEM |
VM_MAP_WIRE_NOHOLES);
pMemFreeBSD->Core.pv =3D (void *)MapAddress;
*ppMem =3D &pMemFreeBSD->Core;
return VINF_SUCCESS;
>
> Regards,
> Alexander Eichner
>
> [1] http://www.virtualbox.org/browser/trunk/src/VBox/Runtime/r0drv/freebs=
d/memobj-r0drv-freebsd.c?rev=3D26899
> [2]http://fxr.watson.org/fxr/source/amd64/amd64/pmap.c?im=3Dbigexcerpts#L=
3076
>
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