On Fri, Jul 17, 2020 at 2:00 AM Philippe Mathieu-Daudé <f4...@amsat.org> wrote:
>
> 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
> >>>> <hskinnem...@google.com> wrote:
> >>>>>
> >>>>> On Wed, Jul 15, 2020 at 3:57 AM Philippe Mathieu-Daudé
> >>>>> <f4...@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);
> }
> }
Could someone please remind me what problem we're trying to solve here?
Currently, if the user (or test) doesn't provide a drive, we pass NULL
as the block backend to m25p80. This means we'll take the code path in
m25p_realize() that does
trace_m25p80_binding_no_bdrv(s);
s->storage = blk_blockalign(NULL, s->size);
memset(s->storage, 0xFF, s->size);
which will look like a freshly chip-erased flash chip.
Are we looking for a more elegant way to replace those three lines of
code (+ a couple of conditionals in the writeback paths)?
But we don't even have a dummy device that looks like an erased flash chip...
Havard
