Peter Maydell <peter.mayd...@linaro.org> writes:
> On Wed, 6 Apr 2022 at 21:07, Alex Bennée <alex.ben...@linaro.org> wrote:
>>
>>
>> Peter Maydell <peter.mayd...@linaro.org> writes:
>> > Guest memory is generally zero at startup. Do we manage to
>> > hit the bit of memory at the start of the virt machine's RAM
>> > where we store the DTB ? (As you say, initializing the data
>> > structures is the right thing anyway.)
>>
>> I don't know - where is the DTB loaded?
>
> Start of RAM (that's physaddr 0x4000_0000). The thing I'm not sure
> about is whether these qtests go through the code in hw/arm/boot.c
> that loads the DTB into guest RAM or not.
Yes because it's linked to the machine creation:
Thread 1 hit Breakpoint 1, arm_load_dtb (addr=1073741824,
binfo=binfo@entry=0x55bc4ce26970, addr_limit=0, as=as@entry=0x55bc4d119c50,
ms=ms@entry=0x55bc4ce26800) at ../../hw/arm/boot.c:534
534 {
(rr) bt
#0 arm_load_dtb (addr=1073741824, binfo=binfo@entry=0x55bc4ce26970,
addr_limit=0, as=as@entry=0x55bc4d119c50, ms=ms@entry=0x55bc4ce26800) at
../../hw/arm/boot.c:534
#1 0x000055bc4a9f7ded in virt_machine_done (notifier=0x55bc4ce26910,
data=<optimized out>) at ../../hw/arm/virt.c:1637
#2 0x000055bc4aebc807 in notifier_list_notify (list=list@entry=0x55bc4b5f8b20
<machine_init_done_notifiers>, data=data@entry=0x0) at ../../util/notify.c:39
#3 0x000055bc4a7f82db in qdev_machine_creation_done () at
../../hw/core/machine.c:1235
#4 0x000055bc4a744b19 in qemu_machine_creation_done () at
../../softmmu/vl.c:2725
#5 qmp_x_exit_preconfig (errp=<optimized out>) at ../../softmmu/vl.c:2748
#6 0x000055bc4a748a14 in qmp_x_exit_preconfig (errp=<optimized out>) at
../../softmmu/vl.c:2741
#7 qemu_init (argc=<optimized out>, argv=<optimized out>, envp=<optimized
out>) at ../../softmmu/vl.c:3776
#8 0x000055bc4a6de639 in main (argc=<optimized out>, argv=<optimized out>,
envp=<optimized out>) at ../../softmmu/main.c:49
(ION: yay, I can capture qtest runs in rr now ;-)
>
>> Currently we are using the first
>> couple of pages in qtest because that where the qtest allocater is
>> initialised:
>>
>> static void *qos_create_machine_arm_virt(QTestState *qts)
>> {
>> QVirtMachine *machine = g_new0(QVirtMachine, 1);
>>
>> alloc_init(&machine->alloc, 0,
>> ARM_VIRT_RAM_ADDR,
>> ARM_VIRT_RAM_ADDR + ARM_VIRT_RAM_SIZE,
>> ARM_PAGE_SIZE);
>> qvirtio_mmio_init_device(&machine->virtio_mmio, qts,
>> VIRTIO_MMIO_BASE_ADDR,
>> VIRTIO_MMIO_SIZE);
>>
>> qos_create_generic_pcihost(&machine->bridge, qts, &machine->alloc);
>>
>> machine->obj.get_device = virt_get_device;
>> machine->obj.get_driver = virt_get_driver;
>> machine->obj.destructor = virt_destructor;
>> return machine;
>> }
>>
>> I don't know if there is a more sane piece of memory we should be using.
>
> The first part of RAM is fine, it's just you can't assume it's
> all zeroes :-)
>
> -- PMM
--
Alex Bennée
