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Date:      Mon, 14 Jul 2014 20:53:45 +0300
From:      Konstantin Belousov <kostikbel@gmail.com>
To:        Nathan Whitehorn <nwhitehorn@FreeBSD.org>
Cc:        svn-src-head@freebsd.org, svn-src-all@freebsd.org, src-committers@freebsd.org
Subject:   Re: svn commit: r268624 - head/sys/dev/vt/hw/efifb
Message-ID:  <20140714175345.GK93733@kib.kiev.ua>
In-Reply-To: <201407141742.s6EHgMNt094168@svn.freebsd.org>
References:  <201407141742.s6EHgMNt094168@svn.freebsd.org>

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On Mon, Jul 14, 2014 at 05:42:22PM +0000, Nathan Whitehorn wrote:
> Author: nwhitehorn
> Date: Mon Jul 14 17:42:22 2014
> New Revision: 268624
> URL: http://svnweb.freebsd.org/changeset/base/268624
>=20
> Log:
>   On my Lenovo laptop, the firmware maps the EFI framebuffer with MTRRs s=
et
>   to uncacheable. This leads to execrable console performance. Once PMAP =
is
>   up, remap the framebuffer as write-combining. This reduces boot time on=
 my
>   laptop by 60% when booting with EFI.
>  =20
>   MFC after:	2 weeks
>=20
> Modified:
>   head/sys/dev/vt/hw/efifb/efifb.c
>=20
> Modified: head/sys/dev/vt/hw/efifb/efifb.c
> =3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=3D=
=3D=3D=3D=3D
> --- head/sys/dev/vt/hw/efifb/efifb.c	Mon Jul 14 17:16:09 2014	(r268623)
> +++ head/sys/dev/vt/hw/efifb/efifb.c	Mon Jul 14 17:42:22 2014	(r268624)
> @@ -53,6 +53,7 @@ __FBSDID("$FreeBSD$");
> =20
>  static vd_init_t vt_efifb_init;
>  static vd_probe_t vt_efifb_probe;
> +static void vt_efifb_remap(void *efifb_data);
> =20
>  static struct vt_driver vt_efifb_driver =3D {
>  	.vd_name =3D "efifb",
> @@ -68,6 +69,8 @@ static struct vt_driver vt_efifb_driver=20
>  static struct fb_info local_info;
>  VT_DRIVER_DECLARE(vt_efifb, vt_efifb_driver);
> =20
> +SYSINIT(efifb_remap, SI_SUB_KMEM, SI_ORDER_ANY, vt_efifb_remap, &local_i=
nfo);
> +
>  static int
>  vt_efifb_probe(struct vt_device *vd)
>  {
> @@ -133,9 +136,9 @@ vt_efifb_init(struct vt_device *vd)
>  	info->fb_size =3D info->fb_height * info->fb_stride;
>  	info->fb_pbase =3D efifb->fb_addr;
>  	/*
> -	 * We could use pmap_mapdev here except that the kernel pmap
> -	 * hasn't been created yet and hence any attempt to lock it will
> -	 * fail.
> +	 * Use the direct map as a crutch until pmap is available. Once pmap
> +	 * is online, the framebuffer will be remapped by vt_efifb_remap()
> +	 * using pmap_mapdev_attr().
>  	 */
>  	info->fb_vbase =3D PHYS_TO_DMAP(efifb->fb_addr);
> =20
> @@ -163,3 +166,22 @@ vt_efifb_init(struct vt_device *vd)
> =20
>  	return (CN_INTERNAL);
>  }
> +
> +static void
> +vt_efifb_remap(void *xinfo)
> +{
> +	struct fb_info *info =3D xinfo;
> +
> +	if (info->fb_pbase =3D=3D 0)
> +		return;
> +
> +	/*
> +	 * Remap as write-combining. This massively improves performance and
> +	 * happens very early in kernel initialization, when everything is
> +	 * still single-threaded and interrupts are off, so replacing the
> +	 * mapping address is safe.
> +	 */
> +	info->fb_vbase =3D (intptr_t)pmap_mapdev_attr(info->fb_pbase,
> +	    info->fb_size, VM_MEMATTR_WRITE_COMBINING);
> +}
> +
Could you use pmap_change_attr() ? This would save some KVA.

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