Hi,
On 29/11/25 02:09, Matthew Wilcox wrote:
On Fri, Nov 28, 2025 at 03:41:40PM +1100, Jordan Niethe wrote:
A consequence of placing the device private pages outside of the
physical address space is that they no longer have a PFN. However, it is
still necessary to be able to look up a corresponding device private
page from a device private PTE entry, which means that we still require
some way to index into this device private address space. This leads to
the idea of a device private PFN. This is like a PFN but instead of
Don't call it a "device private PFN". That's going to lead to
confusion. Device private index? Device memory index?
Sure, I think 'device memory index' is fine. What I was trying to
express with 'device private PFN' here is that each index into device
memory still represents a PAGE_SIZE region, but I agree it leads to
further confusion.
Thanks,
Jordan.
By removing the device private pages from the physical address space,
this RFC also opens up the possibility to moving away from tracking
device private memory using struct pages in the future. This is
desirable as on systems with large amounts of memory these device
private struct pages use a signifiant amount of memory and take a
significant amount of time to initialize.
I did tell Jerome he was making a huge mistake with his design, but
he forced it in anyway.
