Re: [help] Xen 4.14.5 on Devuan 4.0 Chimaera, regression from Xen 4.0.1

[Andrew Cooper <andrew.cooper3@xxxxxxxxxx>]

On 14/03/2023 4:48 pm, Denis wrote:
> On 14.03.2023 16:11, Andrew Cooper wrote:
>> On 14/03/2023 2:53 pm, Denis wrote:
>>> On 14.03.2023 07:37; Jan Beulich wrote:
>>>> On 14.03.2023 02:15, Denis wrote:
>>>>> On 13.03.2023 10:36, Jan wrote
>>>>>> On 10.03.2023 21:50, Denis wrote:
>>>>>>> Should I test something else?
>>>>>> ... there was no request for any further testing here, for the moment.
>>>>> ah...sorry, going by "Would be nice to have this confirmed forthe system
>>>>> in question, i.e. without Xen underneath Linux" I thought I could test
>>>>> something which might help shed some light on all of this.
>>>> Well, yes, that Linux-without-Xen test would still be useful to have
>>>> results from. I didn't account for this in my earlier reply because
>>>> I had asked for it before already, and I did take "something else"
>>>> for meaning anything that might have turned up as useful from the new
>>>> data you had provided.
>>> What tests could I do or what info should I provide to help?
>> Can you please rebuild Xen with this patch:
>>
>> diff --git a/xen/drivers/passthrough/amd/iommu_acpi.c
>> b/xen/drivers/passthrough/amd/iommu_acpi.c
>> index 2fdebd2d74c9..747eae25f56c 100644
>> --- a/xen/drivers/passthrough/amd/iommu_acpi.c
>> +++ b/xen/drivers/passthrough/amd/iommu_acpi.c
>> @@ -1033,7 +1033,7 @@ static int __init parse_ivrs_table(struct
>> acpi_table_header *table)
>>      const struct acpi_ivrs_header *ivrs_block;
>>      unsigned long length;
>>      unsigned int apic;
>> -    bool_t sb_ioapic = !iommu_intremap;
>> +    bool_t sb_ioapic = 1;
>>      int error = 0;
>>  
>>      BUG_ON(!table);
>>
>> which should cause the behaviour to revert back to that of Xen 4.0.1 
>> (i.e. it will fully ignore the checks relating to the southbridge ioapic).
>>
>> Confirm that with this, and booting Xen simply with `iommu=1` that full
>> DMA remapping and interrupt remapping is considered active.
>>
>>
>> Then, can you play around with passing the soundblaster through to VMs. 
>> Looking at the LSPCI you provided, it only supports legacy line interrupts.
>>
>> Does the device work fine, or do you get a bunch of errors on `xl dmesg`
>> about IO page faults (which is a generic "IOMMU said no to something"
>> message)?
> Am I right to assume that I would need the source/header packages from 
> the Devuan 4.0 install and then re-compile Xen?

Yes.

`apt build-dep` to install the build dependencies, and `apt source xen`
to get the Xen sources.

All you actually need to do is is a build of xen.gz, not a full build of
everything, which will simplify things massively if you don't want to
rebuild the world.

~Andrew