Messages in this thread | | | Date | Thu, 25 Jun 2015 08:51:47 +0200 | From | Ingo Molnar <> | Subject | Re: [PATCH v2 2/2] x86/mm/pat, drivers/media/ivtv: move pat warn and replace WARN() with pr_warn() |
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* Luis R. Rodriguez <mcgrof@do-not-panic.com> wrote:
> From: "Luis R. Rodriguez" <mcgrof@suse.com> > > On built-in kernels this warning will always splat as this is part > of the module init. Fix that by shifting the PAT requirement check > out under the code that does the "quasi-probe" for the device. This > device driver relies on an existing driver to find its own devices, > it looks for that device driver and its own found devices, then > uses driver_for_each_device() to try to see if it can probe each of > those devices as a frambuffer device with ivtvfb_init_card(). We > tuck the PAT requiremenet check then on the ivtvfb_init_card() > call making the check at least require an ivtv device present > before complaining. > > Reported-by: Fengguang Wu <fengguang.wu@intel.com> [0-day test robot] > Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com> > --- > drivers/media/pci/ivtv/ivtvfb.c | 15 +++++++++------ > 1 file changed, 9 insertions(+), 6 deletions(-) > > diff --git a/drivers/media/pci/ivtv/ivtvfb.c b/drivers/media/pci/ivtv/ivtvfb.c > index 4cb365d..8b95eef 100644 > --- a/drivers/media/pci/ivtv/ivtvfb.c > +++ b/drivers/media/pci/ivtv/ivtvfb.c > @@ -38,6 +38,8 @@ > Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA > */ > > +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt > + > #include <linux/module.h> > #include <linux/kernel.h> > #include <linux/fb.h> > @@ -1171,6 +1173,13 @@ static int ivtvfb_init_card(struct ivtv *itv) > { > int rc; > > +#ifdef CONFIG_X86_64 > + if (pat_enabled()) { > + pr_warn("ivtvfb needs PAT disabled, boot with nopat kernel parameter\n"); > + return -ENODEV; > + } > +#endif > + > if (itv->osd_info) { > IVTVFB_ERR("Card %d already initialised\n", ivtvfb_card_id); > return -EBUSY;
Same argument as for ipath: why not make arch_phys_wc_add() fail on PAT and return -1, and check it in arch_phys_wc_del()?
That way we don't do anything drastic, the remaining few drivers still keep working (albeit suboptimally - can be worked around with the 'nopat' boot option) - yet we've reduced the use of MTRRs drastically.
Thanks,
Ingo
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