Hello Guys,
Just following up to see if we decided on what is the next step regarding where the DMA description is going?
anmar
On 26 August 2013 11:06, Al Stone al.stone@linaro.org wrote:
On 08/25/2013 09:35 PM, Hanjun Guo wrote:
Hi everyone,
I read the wiki about ACPI Table Prioritization: https://wiki.linaro.org/LEG/Engineering/Kernel/ACPI/TablePriorities
and I noticed that CSRT is in the *Never Tables* priority, here I got some different opinions.
Yes, CSRT or Core System Resources Table is a proprietary ACPI table introduced by Microsoft, but This table can contain devices that are not in the system DSDT table. In particular DMA controllers, Timer, interrupt might be described here.
we can get DMA description from DMAR (DMA Remapping Table) tables on Intel platform, but on ARM SoCs, there is no table to describe DMA, only CSRT is available.
Actually, the support code of CSRT in Linux kernel already have submitted by Intel on Jan 17 this year, but only DMA is supported, still have something more to do (if needed).
So, why not use the CSRT table to describe DMA?
Thanks Hanjun
The simple answer is that there has been no feedback on the prioritization -- up until now. Really! Hanjun has the honor of providing the first substantive feedback for the page :).
Just the same, that wiki page was written based on my best guess at the time. Let's just fix it if it's wrong.
I had not thought about using the CSRT for the DMA description. I'll take a look at that. I had several discussions with both Elsie and Leo at LCE13 about needing something similar to the DMAR (or the AMD equivalent) but specific to ARM. However, our discussion was more from the standpoint of the needs of virtualization so we may still need a new table or something derived from the DMAR.
-- ciao, al
Al Stone Software Engineer Linaro Enterprise Group al.stone@linaro.org