Hi All,
We still have some issues with PCI cards in our FSL P5020 and P5040
systems since the DMA mapping updates. [1, 2]
We have to limit the RAM to 3500MB for some problematic PCI cards.
(kernel boot argument 'mem=3500M')
The problematic DMA mapping code was added with the PowerPC updates
4.21-1 to the official kernel source code last year. [3]
We have created a bug report. [4]
The old 4.x kernels aren't affected because they use the old DMA code.
Please check the new DMA code again.
Thanks,
Christian
[1]
http://forum.hyperion-entertainment.com/viewtopic.php?f=58&p=49486#p49486
[2]
http://forum.hyperion-entertainment.com/viewtopic.php?f=58&t=4349&start=50#p49099
[3]
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=8d6973327ee84c2f40dd9efd8928d4a1186c96e2
[4] https://bugzilla.kernel.org/show_bug.cgi?id=205201
On 28 November 2018 at 4:55 pm, Christian Zigotzky wrote:
On 28 November 2018 at 12:05PM, Michael Ellerman wrote:
Nothing specific yet.
I'm a bit worried it might break one of the many old obscure platforms
we have that aren't well tested.
Please don't apply the new DMA mapping code if you don't be sure if it
works on all supported PowerPC machines. Is the new DMA mapping code
really necessary? It's not really nice, to rewrote code if the old
code works perfect. We must not forget, that we work for the end
users. Does the end user have advantages with this new code? Is it
faster? The old code works without any problems. I am also worried
about this code. How can I test this new DMA mapping code?
Thanks
