Hi,
On 23/08/2021 16:15, Moustafa Nofal wrote:
>>Last warning. :)
>
>>You answer in html inside response and use strange formatting: it's
>>really hard to read your mails and a fiddling finding out the spots
>>where you responded.
> I deleted the whole message and am answering to your message exactly,
> sorry for disturbance.
Reply-to-all…
>
>>You need to use MAP_UNCACHED for MMIO devices. But keep in mind that we
>>use huge pages on arm, so 2MiB will get mapped, but that shouldn't be an
>>issue in your case.
>
>> I could not find a signature, but I think I need a void pointer with
>> address as an argument, am I correct?
>
>>How can you even not find the signature? There's nothing easier like that:
>>$ git grep map_range
>>void map_range(void *start, unsigned long size, enum map_type map_type)
>
>>But yes, besides you should use MAP_UNCACHED, this looks good.
>
> Yes, I have done all of this till here
>
>
>>OK - I think I don't understand what you refer to with "signature".
>
>
>>>Ok, now things get a bit complicated:
>
>>Usually, the finest granularity for assigning memory is the PAGE_SIZE,
>>which is, in case of ARM, 4KiB (0x1000). If you map anything below
>>0x1000 (e.g., 0xb4), then Jailhouse implements subpaging: The hypervisor
>>will trap on access, and dispatch the access. In this case, you must
>>specify JAILHOUSE_MEM_IO_${WIDTH} (with WIDTH=8,16,32,64), in order to
>>allow access within a specified width.
>
> Yes, this was tricky and I made your recommendation and used
> JAILHOUSE_MEM_IO_32 in inmate configuration file.
>
>>Otherwise, you will fault, as you can see here. "size 4" tells you that
>>the width was 4*8=32 bit (obviously, you used mmio_write32).
>
>>So now there are two possibilities how you can fix this issue:
>
>>1. Change the config flags of the memory region to:
>>.flags = JAILHOUSE_MEM_READ | JAILHOUSE_MEM_WRITE |
>>JAILHOUSE_MEM_IO | JAILHOUSE_MEM_IO_32
>
>>Advantage: You *exactly* only map 0xb4 byte of the device
>>Disadvantage: The hypervisor will trap on every access
> This option is working and does not contradict with the concept of
> static partitioning. There are different Peripherals in this area and It
> would be better to distribute on cells.
Depends on your goals and /how/ exactly you define static partitioning.
Still, in case there are different peripherals then subpaging is
probably the way to go.
>
>>2. Change .size from 0xb4 to 1*PAGE_SIZE. This will map 4KiB instead of
>>0xb4 byte. If there are no other devices behind that physical memory
>>region, then this should be the preferred choice, as no further
>>hypervisor activity will be involved.
>
> I used the first option and it is working like a charm. The second
Fine!
> option I tried with .size=0x1000 and I got:
> unhandled data write at 0xfe2000020(4), which is the GPIO_SET_Register
> unhandled trap (exception class 0x24)
> Then CPU 0 was parked
>
> unhandled data write at 0xfe2000028(4), which is the GPIO_CLR_Register
> unhandled trap (exception class 0x24)
> Then CPU 2 was parked
... Did you assign those two CPUs to the cell? It looks like someone
else would access those register (ie, the root cell?)
Ralf
>
> So, I will avoid it apparently, unless you have an idea.
> Thanks so much for your help and I tried to avoid HTML emails as much as
> I can.
>
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