Hi Catalin:
        The commit 3690951fc6d42f3a0903987677d0e592c49dd8db(arm64: Use swiotlb 
late initialisation)
switches the DMA mapping code to swiotlb_tlb_late_init_with_default_size(), 
this will occur a problem
when I run the scsi stress tests, the message as below:

        sas_controller b1000000.sas: swiotlb buffer is full (sz: 65536 bytes)..
        DMA: Out of SW-IOMMU space for 65536 bytes at device b1000000.sas

The reason is that the swiotlb_tlb_late_init_with_default_size() could only 
alloc 16M memory for DMA-mapping,
and the param in cmdline "swiotlb=xxx" is useless because the get_free_pages() 
only use the buddy to assigned a
maximum memory of 16M(The MAX_ORDER is 13 for 4k pages), obviously 16M is too 
small in many scenes, but
the swiotlb_init() which could reserved a bigger memory as wished could work 
well for most drivers.

I could not get a better way to fix this problem except to revert this patch, 
so could you please give me some
advise and help me, thanks very much.

Regards
Ding

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majord...@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/

Reply via email to