IssueRaiser

Linus has said that the pain point actually starts around 1GB, especially when using a 3/1 userspace/kernel address split.

Linus has said that the pain point actually starts around 1GB, especially when using a 3/1 userspace/kernel address split. At 1GB, you can't map the entirety of physical ram into kernel address space simultaneously, since you also have memory-mapped IO taking up space. Let alone mapping the same physical memory to multiple virtual addresses with different cache attributes, which is useful because approximately none of these SoCs have full cache coherence across all hardware blocks.

Posted by brigade on Aug 12, 2014, 8:12 AM

Tags

Related issues

Raise real-world problems, find people facing the same issue, and discuss solutions.9,000 issues0 comments

hackernews (Other)

Linus has said that the pain point actually starts around 1GB, especially when using a 3/1 userspace/kernel address split.

brigadeAug 12, 2014, 8:12 AM

Linus has said that the pain point actually starts around 1GB, especially when using a 3/1 userspace/kernel address split. At 1GB, you can't map the entirety of physical ram into kernel address space simultaneously, since you also have memory-mapped IO taking up space. Let alone mapping the same physical memory to multiple virtual addresses with different cache attributes, which is useful because approximately none of these SoCs have full cache coherence across all hardware blocks.

Comments (0)

No comments yet. Start the discussion.

Comment on this issue