Yes, apparently 0xdfffc is in ROM area for QEMU (0xc0000 -- 0xe0000,
defined in include/hw/loader.h). The next thing to figure out is why
u-boot uses it as a stack area.
Best regards,
Anton Gerasimov
On 11/10/2017 06:04 PM, Anton Gerasimov wrote:
> New guess:
>
> in the most safe configuration of u-boot (CONFIG_SMP=n, lacpi disabled)
> with Igor's patch applied `qemu-system-i386 -bios /path/to/uboot.rom`
> fails on the first 'ret' instruction. GDB shows that memory at $esp
> (0xdfffc at the entrance to board_init_f_mem) and everything around it
> is zero despite 'call' and 'push' instructions executed. If you go one
> commit before the breaking one it works fine, stuff gets put onto stack.
> Could it that be that stack itself is in this 'readonly' area?
>
> Thanks,
> Anton Gerasimov
>
> On 11/09/2017 02:58 AM, Bin Meng wrote:
>> On Wed, Nov 8, 2017 at 9:05 PM, Anton Gerasimov
>> <an...@advancedtelematic.com> wrote:
>>> Adding Igor Mammedov to the loop.
>>>
>> Really add Igor Mammedov.
>>
>> Igor, can you help look at this?
>>
>>> On 11/08/2017 01:59 PM, Anton Gerasimov wrote:
>>>> To whoever might be interested: I've bisected qemu and the breaking
>>>> commit is 208fa0e43645edd0b0d8f838857dfc79daff40a8 (pc: make 'pc.rom'
>>>> readonly when machine has PCI enabled). It's just three lines added,
>>>> I'll paste the whole patch here. Not quite sure what can we do here though.
>>>>
>>>>
>>>> diff --git a/hw/i386/pc.c b/hw/i386/pc.c
>>>> index 22e16031b0..59435390ba 100644
>>>> --- a/hw/i386/pc.c
>>>> +++ b/hw/i386/pc.c
>>>> @@ -1443,6 +1443,9 @@ void pc_memory_init(PCMachineState *pcms,
>>>> option_rom_mr = g_malloc(sizeof(*option_rom_mr));
>>>> memory_region_init_ram(option_rom_mr, NULL, "pc.rom", PC_ROM_SIZE,
>>>> &error_fatal);
>>>> + if (pcmc->pci_enabled) {
>>>> + memory_region_set_readonly(option_rom_mr, true);
>>>> + }
>>>> memory_region_add_subregion_overlap(rom_memory,
>>>> PC_ROM_MIN_VGA,
>>>> option_rom_mr,
>>>>
>>>>
>> Regards,
>> Bin
>
--
Anton Gerasimov, ATS Advanced Telematic Systems GmbH
Kantstrasse 162, 10623 Berlin
Managing Directors: Dirk Pöschl, Armin G. Schmidt
Register Court: HRB 151501 B, Amtsgericht Charlottenburg
