Re: [PATCH v5 10/11] hw/arm: Wire up BMC boot flash for npcm750-evb and quanta-gsj

[Philippe Mathieu-Daudé]

On 7/17/20 10:27 AM, Philippe Mathieu-Daudé wrote:
> On 7/17/20 10:03 AM, Thomas Huth wrote:
>> On 17/07/2020 09.48, Philippe Mathieu-Daudé wrote:
>>> +Thomas
>>
>>> On 7/16/20 10:56 PM, Havard Skinnemoen wrote:
>>>> On Wed, Jul 15, 2020 at 1:54 PM Havard Skinnemoen
>>>> <hskinnemoen@google.com> wrote:
>>>>>
>>>>> On Wed, Jul 15, 2020 at 3:57 AM Philippe Mathieu-Daudé <f4bug@amsat.org> 
>>>>> wrote:
>>>>>>
>>>>>> On 7/15/20 11:00 AM, Markus Armbruster wrote:
>>>>>>> Now my point.  Why first make up user configuration, then use that to
>>>>>>> create a BlockBackend, when you could just go ahead and create the
>>>>>>> BlockBackend?
>>>>>>
>>>>>> CLI issue mostly.
>>>>>>
>>>>>> We can solve it similarly to the recent "sdcard: Do not allow invalid SD
>>>>>> card sizes" patch:
>>>>>>
>>>>>>  if (!dinfo) {
>>>>>>      error_setg(errp, "Missing SPI flash drive");
>>>>>>      error_append_hint(errp, "You can use a dummy drive using:\n");
>>>>>>      error_append_hint(errp, "-drive if=mtd,driver=null-co,"
>>>>>>                              "read-ones=on,size=64M\n);
>>>>>>      return;
>>>>>>  }
>>>>>>
>>>>>> having npcm7xx_connect_flash() taking an Error* argument,
>>>>>> and MachineClass::init() call it with &error_fatal.
>>>>>
>>>>> Erroring out if the user specifies a configuration that can't possibly
>>>>> boot sounds good to me. Better than trying to come up with defaults
>>>>> that are still not going to result in a bootable system.
>>>>>
>>>>> For testing recovery paths, I think it makes sense to explicitly
>>>>> specify a null device as you suggest.
>>>>
>>>> Hmm, one problem. qom-test fails with
>>>>
>>>> qemu-system-aarch64: Missing SPI flash drive
>>>> You can add a dummy drive using:
>>>> -drive if=mtd,driver=null-co,read-zeroes=on,size=32M
>>>> Broken pipe
>>>> /usr/local/google/home/hskinnemoen/qemu/for-upstream/tests/qtest/libqtest.c:166:
>>>> kill_qemu() tried to terminate QEMU process but encountered exit
>>>> status 1 (expected 0)
>>>> ERROR qom-test - too few tests run (expected 68, got 7)
>>>>
>>>> So it looks like we might need a different solution to this, unless we
>>>> want to make generic tests more machine-aware...
>>
>> I didn't follow the other mails in this thread, but what we usually do
>> in such a case: Add a "if (qtest_enabled())" check to the device or the
>> machine to ignore the error if it is running in qtest mode.
> 
> Hmm I'm not sure it works in this case. We could do:
> 
>   if (!dinfo) {
>      if (qtest) {
>         /* create null drive for qtest */
>         opts = ...;
>         dinfo = drive_new(opts, IF_MTD, &error_abort);
>      } else {
>         /* teach user to use proper CLI */
>         error_setg(errp, "Missing SPI flash drive");
>         error_append_hint(errp, "You can use a dummy drive using:\n");
>         error_append_hint(errp, "-drive if=mtd,driver=null-co,"
>                                 "read-ones=on,size=64M\n);
>      }
>   }
> 
> But I'm not sure Markus will enjoy it :)
> 
> Markus, any better idea about how to handle that with automatic qtests?

FWIW IDE device has a concept of "Anonymous BlockBackend for an empty
drive":

static void ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind, Error **errp)
{
    IDEBus *bus = DO_UPCAST(IDEBus, qbus, dev->qdev.parent_bus);
    IDEState *s = bus->ifs + dev->unit;
    int ret;

    if (!dev->conf.blk) {
        if (kind != IDE_CD) {
            error_setg(errp, "No drive specified");
            return;
        } else {
            /* Anonymous BlockBackend for an empty drive */
            dev->conf.blk = blk_new(qemu_get_aio_context(), 0,
BLK_PERM_ALL);
            ret = blk_attach_dev(dev->conf.blk, &dev->qdev);
            assert(ret == 0);
        }
    }