Hi Greg,
I tried specifying a full triple but it's still the same issue.
(lldb) target create --arch=mips64el-pc-linux "coredump.elf" --core "core_mips"
error: Unable to find process plug-in for core file
'/home/battarde/test/core_mips'
LLDB correctly recognises that "core_mips" is a core file and creates an
appropriate Process instance (i.e ProcessElfCore).
But then "ProcessElfCore::CanDebug" fails as it cannot create a complete Module
because it cannot find any architecture in that core file.
Everything in the triple for the core file "core_mips" remains "Unknown" here
i.e UnknownArch-UnknownVendor-UnknownOS/UnknownEnvironment.
What happens here is, "ObjectFileELF::GetModuleSpecifications" has this:
const uint32_t sub_type = subTypeFromElfHeader(header);
spec.GetArchitecture().SetArchitecture(eArchTypeELF,
header.e_machine,
sub_type,
header.e_ident[EI_OSABI]);
subTypeFromElfHeader(header) returns ArchSpec::eMIPSSubType_unknown (as
header.e_flags is 0).
Then SetArchitecture called with cpu=llvm::ELF::EM_MIPS and
sub_type=ArchSpec::eMIPSSubType_unknown fails to find a ArchDefinitionEntry
because there ins't any ArchDefinitionEntry in g_elf_arch_entries for this
cpu/subtype combination.
This in turn leaves everything in triple as "Unknown" and the ArchSpec created
for core file remains Invalid.
-Bhushan
-----Original Message-----
From: Greg Clayton [mailto:gclay...@apple.com]
Sent: 11 March 2016 02:31
To: Bhushan Attarde
Cc: lldb-dev@lists.llvm.org
Subject: Re: [lldb-dev] Not able to find process plugin for core file
> On Mar 10, 2016, at 4:34 AM, Bhushan Attarde via lldb-dev
> <lldb-dev@lists.llvm.org> wrote:
>
> Hi All,
>
> I am working on adding support for MIPS coredump file in LLDB.
>
> I tried below command:
>
> (lldb) target create "app_mips.elf" --core "core_mips"
> error: Unable to find process plug-in for core file '/home/battarde/test/
> core_mips’
>
> Currently LLDB is not able to find a Process plugin for MIPS core file. I
> debugged this and found that while finding the process plugin,
> "ProcessElfCore::CanDebug" calls "ModuleList::GetSharedModule"
> to create a Module for corefile. But Module constructor in Module.cpp has
> this:
>
> // First extract all module specifications from the file using the local
> // file path. If there are no specifications, then don't fill anything in
> ModuleSpecList modules_specs;
> if (ObjectFile::GetModuleSpecifications(module_spec.GetFileSpec(), 0, 0,
> modules_specs) == 0)
> return;
>
> The issue here is that the targets like MIPS depends on elf flags to
> determine the actual architecture but core file doesn't contain any arch
> information (header.e_flags is 0) so it can't decide the arch contained in
> core file.
> As no specifications are found, Module constructor takes an early exit
> leaving its members uninitialized.
>
> Going further, Module also fails to get the ObjectFile representation as it
> doesn't contain enough information (Module::m_file, Module::m_arch) required
> to get ObjectFile.
>
> So, "ProcessElfCore::CanDebug" returns false and because of this LLDB gives
> error saying that it is unable to find process plug-in for core file.
>
> I can make mipsVariantFromElfFlags() to return some default architecture (to
> ensure we always have valid arch when it can't be decided from elf flags) but
> this won't always work (core's default arch and executable_elf's arch may not
> "match" always).
> What could be the proper fix to this issue?
Try specifying a full triple when creating the target:
(lldb) target create --arch=mips32-pc-linux "app_mips.elf" --core "core_mips"
If any ELF file is unable to figure out its file type, it should leave things
generic so the triple for the core ELF file should be something like:
"mips-*-*". If that is true, then this should match your more specific triple
specified in the target of "mips32-pc-linux".
Try out specifying the triple and let me know how that goes.
Greg Clayton
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