Hi,
On 2025/2/3 19:14, Lucas Stach wrote:
Hi Sui,
Am Montag, dem 03.02.2025 um 18:53 +0800 schrieb Sui Jingfeng:
Hi,
On 2025/2/3 16:59, Lucas Stach wrote:
Hi Sasha,
Am Samstag, dem 01.02.2025 um 23:33 -0500 schrieb Sasha Levin:
This is a note to let you know that I've just added the patch titled
drm/etnaviv: Drop the offset in page manipulationto the 6.12-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git%3Ba=su...
The filename of the patch is: drm-etnaviv-drop-the-offset-in-page-manipulation.patch and it can be found in the queue-6.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree, please let stable@vger.kernel.org know about it.
please drop this patch and all its dependencies from all stable queues.
While the code makes certain assumptions that are corrected in this patch, those assumptions are always true in all use-cases today.
Those patches are harmless even we apply them, and after apply my pitch, it requires less CPU computation, right?
I don't see a reason
I think, if 'sg->offset != 0' could happen or not is really matters here. My argument was that the real data is stored at 'sg_dma_address(sg)', NOT the 'sg_dma_address(sg) - sg->offset'.
As we can create a test that we store some kind of data at the middle of a BO by the CPU, then map this BO with the MMU and ask the GPU fetch the data. Do we really have a way tell the GPU to skip the leading garbage data?
to introduce this kind of churn to the stable trees
If I'm wrong or miss something, we can get them back, possibly with new features, additional description, and comments for use-cases. My argument just that we don't have good reasons to take the'sg->offset' into account for now.
to fix a theoretical issue.
The start PA of a buffer segment has been altered, but the corresponding VA is not.
Maybe a approach has to guarantee correct in the theory first.
I'm aware that one could construct cases where things fall over with the previous code. However, there is no such case in practice. I fully agree that this issue should be fixed, which is obviously why I merged the patch.
I do not agree to introduce churn into the stable trees and burden myself and others to check the correctness of the backports (just because patches do apply to the stable tree does not mean all their prerequisites and underlying assumptions are met),
The core problem still is, whether 'sg->offset != 0' will happen or not. Without answering this fundamental question I don't think the rest murmurs make technical sense.
The patch is about to stop touching unreasonable part, if stable branches has raised any problem because of this single patch, I think I could help to resolve.
to fix a theoretical issue.
This is concept, not theoretical.
Regards, Lucas