Does vmalloc_to_page returns contiguous physical memory?

Asked Mar 18 '19 at 11:06

Active Feb 22 '22 at 15:02

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Does vmalloc_to_page returns contiguous physical memory ?

I ask because I see that its return value is used for DMA and DMA uses contiguous memory.

Yet, in vmalloc_to_page implementation it does not seem that it creates a contiguous allocation : https://elixir.bootlin.com/linux/v4.5/source/mm/vmalloc.c#L234

edited Feb 22 '22 at 15:02

Marco Bonelli

asked Mar 18 '19 at 11:06

ransh

`vmalloc` doesn't allocate contiguous physical memory. `vmalloc_to_page` returns the page containing an address within a `vmalloc`ed buffer. – Ian Abbott Mar 18 '19 at 12:12
Thanks, so how can it be used for dma usage (see my question) as done in samsung.c ? – ransh Mar 18 '19 at 15:29
1

Because it only uses that for single page transfers. A single page is contiguous. – Ian Abbott Mar 18 '19 at 15:36
I understand now. thx – ransh Mar 20 '19 at 15:56

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