Re: [PATCH] drm/ttm: provide default page protection for UML

From: Anton Ivanov
Date: Thu Sep 02 2021 - 02:19:33 EST

On 02/09/2021 06:52, Randy Dunlap wrote:
On 9/1/21 10:48 PM, Anton Ivanov wrote:
On 02/09/2021 03:01, Randy Dunlap wrote:
boot_cpu_data [struct cpuinfo_um (on UML)] does not have a struct
member named 'x86', so provide a default page protection mode

Mends this build error:
../drivers/gpu/drm/ttm/ttm_module.c: In function ‘ttm_prot_from_caching’:
../drivers/gpu/drm/ttm/ttm_module.c:59:24: error: ‘struct cpuinfo_um’ has no member named ‘x86’
   else if (boot_cpu_data.x86 > 3)

Fixes: 3bf3710e3718 ("drm/ttm: Add a generic TTM memcpy move for page-based iomem")
Signed-off-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
Cc: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Huang Rui <ray.huang@xxxxxxx>
Cc: dri-devel@xxxxxxxxxxxxxxxxxxxxx
Cc: Jeff Dike <jdike@xxxxxxxxxxx>
Cc: Richard Weinberger <richard@xxxxxx>
Cc: Anton Ivanov <anton.ivanov@xxxxxxxxxxxxxxxxxx>
Cc: linux-um@xxxxxxxxxxxxxxxxxxx
Cc: David Airlie <airlied@xxxxxxxx>
Cc: Daniel Vetter <daniel@xxxxxxxx>
  drivers/gpu/drm/ttm/ttm_module.c |    4 ++++
  1 file changed, 4 insertions(+)

--- linux-next-20210901.orig/drivers/gpu/drm/ttm/ttm_module.c
+++ linux-next-20210901/drivers/gpu/drm/ttm/ttm_module.c
@@ -53,6 +53,9 @@ pgprot_t ttm_prot_from_caching(enum ttm_
      if (caching == ttm_cached)
          return tmp;
+#ifdef CONFIG_UML
+    tmp = pgprot_noncached(tmp);
  #if defined(__i386__) || defined(__x86_64__)
      if (caching == ttm_write_combined)
          tmp = pgprot_writecombine(tmp);
@@ -69,6 +72,7 @@ pgprot_t ttm_prot_from_caching(enum ttm_
  #if defined(__sparc__)
      tmp = pgprot_noncached(tmp);
      return tmp;

Patch looks OK.

I have a question though - why all of DRM is not !UML in config. Not like we can use them.

I have no idea about that.
Hopefully one of the (other) UML maintainers can answer you.


We will discuss that and possibly push a patch to !UML that part of the tree. IMHO it is not applicable.



Anton R. Ivanov
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