Hi All,
I released the
RC4-2 of kernel
5.4 because of a new patch for solving the onboard SD card issues today.
New:
X5000/20 and X5000/40: coherent_cache patch by Michael Ellerman for solving the issue with the onboard SD card.
He wrote:
For historical reasons powerpc kernels are built with hard wired knowledge of whether or not DMA accesses are cache coherent. Additionally device trees on powerpc do not typically support the dma-coherent property.
So when we know that DMA is coherent, override arch_of_dma_is_coherent() to tell the drivers/of code that all devices are coherent regardless of whether they have a dma-coherent property.
Benjamin Herrenschmidt wrote:
Fundamentally when you set CONFIG_NOT_COHERENT_CACHE you tell the kernel that your processor isn't snooping the bus for DMA accesses colliding with the caches. Thus SW has to explicitly maintain cache coherency around DMA operations by invalidating or flushing the cache accordingly and by keeping pool(s) of non-cachable memory around to use for the consistent allocator. This slows things down.
Download:
linux-image-5.4-rc4-2-X5000.tar.gz
Screenshot of Ubuntu 10.04.4 LTS PowerPC with the kernel 5.4-rc4-2 on an AmigaOne X5000/40:
Please test it.
Thanks,
Christian