Re: [Qemu-devel] [PATCH v1 2/3] memory: Add sysbus memory device

[Peter Crosthwaite]

On Fri, May 16, 2014 at 3:22 PM, Andreas Färber <address@hidden> wrote:
> Peter,
>
> Am 15.04.2014 04:21, schrieb Peter Crosthwaite:
>> Add a sysbus device consisting of a single ram. This allows for
>> instantiation of RAM just like any other device. There are a number
>> of good reasons to want to do this this:
>>
>> 1: Consistency. RAM is not that special where board level files should
>> have to instantiate it with a completely different API. This reduces
>> complexity of board level development by hiding the memory API
>> completely and handling everything via the sysbus API.
>>
>> 2: Device tree completeness. Ram Now shows up in info-qtree and
>> friends. E.g. Info qtree gives meaningful information under the
>> root system bus:
>>
>>   dev: sysbus-memory, id "zynq.ocm_ram"
>>     size = 262144 (0x40000)
>>     read-only = false
>>     irq 0
>>     mmio 00000000fffc0000/0000000000040000
>>   dev: sysbus-memory, id "zynq.ext_ram"
>>     size = 134217728 (0x8000000)
>>     read-only = false
>>     irq 0
>>     mmio 0000000000000000/0000000008000000
>
> I had warned that I would nack any patch that justifies changes with
> "info qtree", so here's your gentle NAK.
>
> Please help deciding on the following patches, which do show such
> devices the QOM way:
>

So I'm shelving this for the interim anyway. My latests series may
infact obsolete this with full MR qomifcation. You could prehaps just
setup TYPE_MEMORY_REGION_RAM (.parent = TYPE_MEMORY_REGION). Then
object-new and friends can be used to achieve the same set of goals as
stated in this commit message (except #3).

> http://patchwork.ozlabs.org/patch/317224/
> http://patchwork.ozlabs.org/patch/343136/
> http://patchwork.ozlabs.org/patch/347064/
>

Yep, this latest one is already on my "to-review" list.

Regards,
Peter

> Note that this doesn't mean we can't create new SysBusDevices, it means
> the commit message should be changed.
>


> Regards,
> Andreas
>
>>
>> 3: Remove dependence of global state. Board files don't have to
>> explicity request the global singleton (and much unloved)
>> address_space_memory() and go hacking on it. address_space_memory()
>> is still ultimately used, but the ugliness is hidden in one place - the
>> sysbus core (we can fix that another day).
>>
>> 4: Data driven machine creation. There is list discussion on being able
>> to create or append-to sysbus machines in a data-driven way (whether
>> thats from command-line, monitor or scripts or whatever). This patch
>> removes the memory special case from that problem and allows RAM
>> instantiation to come via whatever solutions we come up with sysbus
>> device instantiation.
>>
>> Signed-off-by: Peter Crosthwaite <address@hidden>
>> ---
>>
>>  hw/core/Makefile.objs   |  1 +
>>  hw/core/sysbus-memory.c | 63 
>> +++++++++++++++++++++++++++++++++++++++++++++++++
>>  2 files changed, 64 insertions(+)
>>  create mode 100644 hw/core/sysbus-memory.c
>
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