On 19/02/2024 11:41, Christian König wrote:
Am 19.02.24 um 12:29 schrieb Arnd Bergmann:
On Mon, Feb 19, 2024, at 12:22, Christian König wrote:
Am 17.02.24 um 02:31 schrieb Randy Dunlap:
On 2/16/24 12:24, Arnd Bergmann wrote:
From: Arnd Bergmann <arnd@xxxxxxxx>
The newly added drm_test_buddy_alloc_contiguous() test fails to
link on
32-bit targets because of inadvertent 64-bit calculations:
ERROR: modpost: "__aeabi_uldivmod"
[drivers/gpu/drm/tests/drm_buddy_test.ko] undefined!
ERROR: modpost: "__aeabi_ldivmod"
[drivers/gpu/drm/tests/drm_buddy_test.ko] undefined!
>From what I can tell, the numbers cannot possibly overflow a
32-bit size,
so use different types for these.
I noticed that the function has another possible flaw in that is mixes
what it calls pages with 4KB units. This is a big confusing at best,
or possibly broken when built on machines with larger pages.
Fixes: a64056bb5a32 ("drm/tests/drm_buddy: add alloc_contiguous test")
Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>
Tested-by: Randy Dunlap <rdunlap@xxxxxxxxxxxxx>
I've just pushed a similar patch Mathew came up a bit earlier to
drm-misc-fixes.
Sorry for the noise, I have to catch up on picking up patches for
misc-fixes and misc-next.
Ok, thanks.
Have you looked at how this code works for larger values of PAGE_SIZE?
Is there any need to change other things or will this work with the
hardcoded 4KB chunks?
I haven't looked into the details, but I've pointed out before that
using PAGE_SIZE in the buddy or its test cases would be incorrect.
Background is that the buddy allocator is for devices and those work
independent of the CPU PAGE_SIZE. So it can be that on a CPU with 64k
pages the buddy still needs to work with 4k.
Could be that this is work, but could as well be that this is completely
broken. Arun and Mathew needs to answer this, I haven't tested it nor
reviewed the code.
Yeah, we should not be using PAGE_SIZE or PAGE_SHIFT in drm_buddy.[ch]
and tests/drm_buddy_test.c. The smallest default page size is SZ_4K for
drm_buddy. A patch to fix that would be very welcome. If no takers I can
send something.
Regards,
Christian.
Arnd
