Bug 205201 - Booting halts if Dawicontrol DC-2976 UW SCSI board installed, unless RAM size limited to 3500M

[Christian Zigotzky]

Am 21.11.19 um 14:33 schrieb Robin Murphy:
> On 21/11/2019 12:21 pm, Christian Zigotzky wrote:
>> On 21 November 2019 at 01:16 pm, Christian Zigotzky wrote:
>>> On 21 November 2019 at 08:29 am, Christoph Hellwig wrote:
>>>> On Sat, Nov 16, 2019 at 08:06:05AM +0100, Christian Zigotzky wrote:
>>>>> /*
>>>>>   *  DMA addressing mode.
>>>>>   *
>>>>>   *  0 : 32 bit addressing for all chips.
>>>>>   *  1 : 40 bit addressing when supported by chip.
>>>>>   *  2 : 64 bit addressing when supported by chip,
>>>>>   *      limited to 16 segments of 4 GB -> 64 GB max.
>>>>>   */
>>>>> #define   SYM_CONF_DMA_ADDRESSING_MODE 
>>>>> CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE
>>>>>
>>>>> Cyrus config:
>>>>>
>>>>> CONFIG_SCSI_SYM53C8XX_DMA_ADDRESSING_MODE=1
>>>>>
>>>>> I will configure “0 : 32 bit addressing for all chips” for the 
>>>>> RC8. Maybe this is the solution.
>>>> 0 means you are going to do bounce buffering a lot, which seems
>>>> generally like a bad idea.
>>>>
>>>> But why are we talking about the sym53c8xx driver now?  The last issue
>>>> you reported was about video4linux allocations.
>>>>
>>> Both drivers have the same problem. They don't work if we have more 
>>> than 3.5GB RAM. I try to find a solution until you have a good 
>>> solution. I have already a solution for V4L but I still need one for 
>>> the sym53c8xx driver.
>> OK, you mean that "0" is a bad idea but maybe it works until you have 
>> a solution. ;-)
>
> Is this on the same machine with the funny non-power-of-two 
> bus_dma_mask as your other report? If so, does Nicolas' latest 
> patch[1] help at all?
>
> Robin.
>
> [1] 
> https://lore.kernel.org/linux-iommu/20191121092646.8449-1-nsaenzjulienne@suse.de/T/#u
>
Robin,

I modified the patch and compiled a new RC8 of kernel 5.4 today. (patch 
attached)

We have to wait to Rolands test results with his SCSI PCI card. I tested 
it today but my TV card doesn't work with this patch.

Thanks
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