On 2018-05-02 16:51, Ralf Ramsauer wrote:
>
>
> On 05/01/2018 06:54 PM, Jan Kiszka wrote:
>> On 2018-05-01 10:54, Ralf Ramsauer wrote:
>>> On 04/27/2018 08:21 PM, Jan Kiszka wrote:
>>>> On 2018-04-27 11:36, Ralf Ramsauer wrote:
>>>>> This won't drop symbols that are marked as used.
>>>>>
>>>>> The static, relocateable inmate library lib.a is created by ar. When
>>>>> linking executables, unreferenced symbols may be dropped, even if they
>>>>> are attributed as used.
>>>>>
>>>>> --whole-archive ensures that those symbols will be linked.
>>>>>
>>>>> Whereas on x86, we need --gc-sections.
>>>>
>>>> That's something I do not understand yet: With [1] we will build the
>>>> whole hypervisor, including x86, with --whole-archive, and that works
>>>> fine on x86 as well.
>>>
>>> That's what happens if I compile x86 inmates with --whole-archive
>>> instead of --gc-sections:
>>>
>>> LD
>>> /home/ralf/workspace/jailhouse/inmates/demos/x86/32-bit-demo-linked.o
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/lib32.a(ioapic-32.o): In
>>> function `ioapic_init':
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/ioapic.c:48: undefined
>>> reference to `map_range'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/lib32.a(smp-32.o): In
>>> function `smp_start_cpu':
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/smp.c:59: undefined
>>> reference to `delay_us'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/smp.c:61: undefined
>>> reference to `delay_us'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/lib32.a(pci-32.o): In
>>> function `pci_find_device':
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/../pci.c:47: undefined
>>> reference to `pci_read_config'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/../pci.c:51: undefined
>>> reference to `pci_read_config'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/lib32.a(pci-32.o): In
>>> function `pci_find_cap':
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/../pci.c:61: undefined
>>> reference to `pci_read_config'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/../pci.c:65: undefined
>>> reference to `pci_read_config'
>>> /home/ralf/workspace/jailhouse/inmates/lib/x86/../pci.c:68: undefined
>>> reference to `pci_read_config'
>>>
>>> Interestingly, this only happens to the 32-bit demo inmate.
>>>
>>
>> Because we keep everything, something might be missing now: The 32-bit
>> lib does not provide support for all features that its big 64-bit
>> brother has.
>>
>> I still think this approach is too much of a big hammer. Try
>> --print-gc-sections on your specific problem (uart section loss) and
>> play with --undefined as suggested by the ld man page. Not sure if there
>> is also some linker script statement that can do that trick, but it
>> might be worth checking.
>
> KEEP, together with --whole-archive does the trick:
>
Why still --whole-archive? We should have a clear reason here.
> .uarts : {
> __uarts_array_start = .;
> KEEP(*(.uarts));
> __uarts_array_end = .;
> }
Yeah, there must have been some magic there...
Jan
--
Siemens AG, Corporate Technology, CT RDA IOT SES-DE
Corporate Competence Center Embedded Linux
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