Felix Singer has uploaded this change for review. ( https://review.coreboot.org/c/coreboot/+/47409 )
Change subject: doc/relnotes/4.13: Add note about PCI bus mastering Kconfig options ......................................................................
doc/relnotes/4.13: Add note about PCI bus mastering Kconfig options
Change-Id: I66a636f554d18e08a209a7cfd6a59cf13a88f2e1 Signed-off-by: Felix Singer felixsinger@posteo.net --- M Documentation/releases/coreboot-4.13-relnotes.md 1 file changed, 21 insertions(+), 0 deletions(-)
git pull ssh://review.coreboot.org:29418/coreboot refs/changes/09/47409/1
diff --git a/Documentation/releases/coreboot-4.13-relnotes.md b/Documentation/releases/coreboot-4.13-relnotes.md index 8d19067..c8a78bd 100644 --- a/Documentation/releases/coreboot-4.13-relnotes.md +++ b/Documentation/releases/coreboot-4.13-relnotes.md @@ -58,4 +58,25 @@ It still needs changes in assembly, fixed integer to pointer conversions in C, wrappers for blobs, support for running Option ROMs, among other things.
+### Preperations for dropping PCI bus mastering enablement + +The configuration of PCI bus mastering will be dropped in a future release. For +security reasons, bus mastering should be enabled as late as possible. In +coreboot, it's usually not necessary and payloads should only enable it for +devices they use. Since not all payloads enable bus mastering properly yet, +some Kconfig options were added as an intermediate step to give some sort of +"backwards compatibility", which allow enabling or disabling bus mastering by +groups. + +Currently available groups are: + +* Device of class type "system" +* PCI bridges +* Any devices + +For now, "Any devices" is enabled by default to keep the traditional behaviour, +which also includes all other options. This is currently necessary, for instance, +for libpayload based payloads as the drivers don't enable bus mastering for PCI +bridges. + ### Add significant changes here