1) Is that my patch must work with current MESA driver ? (even MESA doesn't
change any bit of its logic) ?
Yes and it must work with all old versions of Mesa. This is usual the
tricky part to get right and most of my concern right now.
2) is that my patch can let kmd go to a new path (using CONTEXT_CONTROL) with
bump up the KMS version ?
No, not necessary. Bumping the KMS version can only be used to signal to
Mesa that it can use a new feature. E.g. Mesa can then stop to use
CONTEXT_CONTROL in it's IBs, but there isn't any guarantee that it does.
3) will MESA change its logic (align with close OGL driver) and bump up its
version so that new version MESA can work with new version KMS/kmd?
No, usually Mesa is changed in a way so that it works with both old and
new kernel drivers. Only when there is a really good reason (usually
critical bugs in the kernel driver) Mesa will drop support for older
kernel versions.
As I said in my internal mail let's do it like this:
1. Don't touch the preamble flag at all, just keep that handling as it
is for now.
2. Add the CONTEXT_CONTROL with the appropriate handling on context
switch and bump the version number to signal that this is done.
3. When #2 is upstream we hack on Mesa to drop the CONTEXT_CONTROL
packets from it's IBs when it sees the new kernel version.
4. When we release SR-IOV we add some logic to the kernel driver to
ignore the preamble flag.
Regards,
Christian.
Am 06.09.2016 um 11:28 schrieb Liu, Monk:
Hi Bas & Christian
I'm not familiar with the policy of upstream kernel driver, so I cannot say if
your proposal is doable or not,
I have questions:
1) Is that my patch must work with current MESA driver ? (even MESA doesn't
change any bit of its logic) ?
2) is that my patch can let kmd go to a new path (using CONTEXT_CONTROL) with
bump up the KMS version ?
3) will MESA change its logic (align with close OGL driver) and bump up its
version so that new version MESA can work with new version KMS/kmd?
With above question addressed, we can together discuss how to modify
CONTEXT_CONTROL patch
BR Monk
-----Original Message-----
From: Koenig, Christian
Sent: Monday, September 05, 2016 7:57 PM
To: Liu, Monk <[email protected]>
Cc: brahma_hybrid_dev <[email protected]>
Subject: Re: [PATCH] drm/amdgpu:implement CONTEXT_CONTROL (v3)
Another possible solution which just came to my mind: Completely ignore the
preamble flag on the IB on keep the existing preamble handling as it is.
Just insert a CONTEXT_CONTROL package at the beginning of the command
submission controlled by if we have seen a context switch or not and then raise
the driver version number.
Then we can fix Mesa to not emit the CONTEXT_CONTROL commands from the UMD any
more and when SR-IOV comes out we add a handling to ignore the preamble flag in
the kernel when it is activated.
Does that sounds like it should work?
Regards,
Christian.
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