Thank you for looking into this, perhaps I could change the patch (at least in the C part not the python script) to something like: - phdr.p_vaddr = cpu_to_dumpXX(s, memory_mapping->virt_addr); + phdr.p_vaddr = cpu_to_dumpXX(s, memory_mapping->virt_addr) ? cpu_to_dumpXX(s, memory_mapping->virt_addr) : phdr.p_paddr;
So in the case of paging where virt_addr is available we will use it Thanks, -- Jon. On Mon, Jan 7, 2019 at 8:04 PM Laszlo Ersek <ler...@redhat.com> wrote: > > On 01/07/19 13:14, Marc-André Lureau wrote: > > Hi > > > > On Tue, Dec 25, 2018 at 5:52 PM Jon Doron <ari...@gmail.com> wrote: > >> > >> vaddr needs to be equal to the paddr since the dump file represents the > >> physical memory image. > >> > >> Without setting vaddr correctly, GDB would load all the different memory > >> regions on top of each other to vaddr 0, thus making GDB showing the wrong > >> memory data for a given address. > >> > >> Signed-off-by: Jon Doron <ari...@gmail.com> > > > > This is a non-trivial patch! (qemu-trivial, please ignore). > > > >> --- > >> dump.c | 4 ++-- > >> scripts/dump-guest-memory.py | 1 + > >> 2 files changed, 3 insertions(+), 2 deletions(-) > >> > >> diff --git a/dump.c b/dump.c > >> index 4ec94c5e25..bf77a119ea 100644 > >> --- a/dump.c > >> +++ b/dump.c > >> @@ -192,7 +192,7 @@ static void write_elf64_load(DumpState *s, > >> MemoryMapping *memory_mapping, > >> phdr.p_paddr = cpu_to_dump64(s, memory_mapping->phys_addr); > >> phdr.p_filesz = cpu_to_dump64(s, filesz); > >> phdr.p_memsz = cpu_to_dump64(s, memory_mapping->length); > >> - phdr.p_vaddr = cpu_to_dump64(s, memory_mapping->virt_addr); > >> + phdr.p_vaddr = phdr.p_paddr; > > > > This is likely breaking paging=true somehow, which sets > > memory_mapping->virt_addr to non-0. > > > > According to doc "If you want to use gdb to process the core, please > > set @paging to true." > > > > Although I am not able to (gdb) x/10bx 0xa0000 for example on a core > > produced with paging. Not sure why, anybody could help? > > > >> assert(memory_mapping->length >= filesz); > >> > >> @@ -216,7 +216,7 @@ static void write_elf32_load(DumpState *s, > >> MemoryMapping *memory_mapping, > >> phdr.p_paddr = cpu_to_dump32(s, memory_mapping->phys_addr); > >> phdr.p_filesz = cpu_to_dump32(s, filesz); > >> phdr.p_memsz = cpu_to_dump32(s, memory_mapping->length); > >> - phdr.p_vaddr = cpu_to_dump32(s, memory_mapping->virt_addr); > >> + phdr.p_vaddr = phdr.p_paddr; > >> > >> assert(memory_mapping->length >= filesz); > >> > >> diff --git a/scripts/dump-guest-memory.py b/scripts/dump-guest-memory.py > >> index 198cd0fe40..2c587cbefc 100644 > >> --- a/scripts/dump-guest-memory.py > >> +++ b/scripts/dump-guest-memory.py > >> @@ -163,6 +163,7 @@ class ELF(object): > >> phdr = get_arch_phdr(self.endianness, self.elfclass) > >> phdr.p_type = p_type > >> phdr.p_paddr = p_paddr > >> + phdr.p_vaddr = p_paddr > > > > With your proposed change though, I can dump memory with gdb... > > > >> phdr.p_filesz = p_size > >> phdr.p_memsz = p_size > >> self.segments.append(phdr) > >> -- > >> 2.19.2 > >> > >> > > > > > > I've never used paging-enabled dumps. First, because doing so requires > QEMU to trust guest memory contents (see original commit 783e9b4826b9; > or more recently/generally, the @dump-guest-memory docs in > "qapi/misc.json"). Second, because whenever I had to deal with guest > memory dumps, I always used "crash" (which needs no paging), and the > subject guests were all Linux. > > I can't comment on paging-enabled patches for dump, except that they > shouldn't regress the paging-disabled functionality. :) If the patches > satisfy that, I'm fine. > > (I *am* surprised that GDB insists on p_vaddr equaling p_paddr; after > all, in the guest, the virtual address is "memory_mapping->virt_addr". > But, I would never claim to understand most of the ELF intricacies, > and/or what GDB requires on top of those.) > > Thanks > Laszlo
