** Changed in: ubuntu-z-systems
Status: New => Triaged
** Changed in: linux (Ubuntu)
Status: New => Triaged
** Changed in: linux (Ubuntu)
Assignee: Skipper Bug Screeners (skipper-screen-team) => Frank Heimes
(fheimes)
** Changed in: ubuntu-z-systems
Assignee: (unassigned) => Frank Heimes (fheimes)
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https://bugs.launchpad.net/bugs/1866162
Title:
[UBUNTU 20.04] ZPCI used write back addresses by default but should
use write through
Status in Ubuntu on IBM z Systems:
Triaged
Status in linux package in Ubuntu:
Triaged
Bug description:
In the initial MIO support introduced in
commit 71ba41c9b1d9 ("s390/pci: provide support for MIO instructions")
setting up the PCI BAR resources defaults to using the
mio_wb address as the resource's start address.
This means users of the mapping, which includes most drivers, will get
write combining on PCI Stores.
his may lead to problems when drivers expect write through
behavior when not using an explicit ioremap_wc() which is the default
behavior on other platforms.
The attached patch changes the default to write through.
It has already been reviewed and is currently queued to be send for
Linux 5.6-rc5 with a CC stable tag.
To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu-z-systems/+bug/1866162/+subscriptions
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