Re: [PATCH v2] loongarch/mm: disable WUC for pgprot_writecombine as same as ioremap_wc

[Icenowy Zheng]

在 2024-12-19星期四的 10:54 +0800，Sui Jingfeng写道：
> 
> On 2024/12/18 20:43, Icenowy Zheng wrote:
> > For the fact of drm/ast's dramatical drop, it's because write to
> > the
> > framebuffer can no longer be reordered.
> 
> 
> No, your understanding is wrong, very very wrong and a big wrong.
> 
> It's not because it can't reorder the write. Rather, it's because
> that the CPU can't do write gathering and can't do burst write any
> more.

Write gathering is a kind of write reordering, comparing to strongly
ordered writing (which is literally one byte per write).

> 
> So do you still think your patch is harmless?

Well, I said that performance w/o correctness is meaningless.

> 
>