[U-Boot] [PATCH 1/1] cmd/bdinfo: sandbox: print the relocation offset

[Bin Meng]

Hi Heinrich,

On Mon, Aug 12, 2019 at 7:17 PM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
>
> On 8/12/19 6:07 AM, Bin Meng wrote:
> > On Sat, Aug 10, 2019 at 5:35 AM Heinrich Schuchardt <xypron.glpk at gmx.de> wrote:
> >>
> >> On the sandbox provide the relocation offset. This value can be used for
> >> debugging with GDB using the `add-symbol-file u-boot <reloc off>' command.
> >>
> >> Signed-off-by: Heinrich Schuchardt <xypron.glpk at gmx.de>
> >> ---
> >>   cmd/bdinfo.c | 1 +
> >>   1 file changed, 1 insertion(+)
> >>
> >> diff --git a/cmd/bdinfo.c b/cmd/bdinfo.c
> >> index 86c17dc427..560c039d37 100644
> >> --- a/cmd/bdinfo.c
> >> +++ b/cmd/bdinfo.c
> >> @@ -395,6 +395,7 @@ int do_bdinfo(cmd_tbl_t *cmdtp, int flag, int argc, char * const argv[])
> >>
> >>          print_bi_boot_params(bd);
> >>          print_bi_dram(bd);
> >> +       print_num("reloc off", (uintptr_t)(gd->reloc_off + gd->arch.ram_buf));
> >
> > Shouldn't we print gd->relocaddr directly?
>
> There are three address spaces involved:
>
> * The physical address space that you see on the address lines of the RAM.
> * The virtual address space of the process in the operating system which
> is mapped by the MMU to the physical address space. This is the address
> space from which memory is allocated by calling mmap().
> * The virtual address space use for testing by the sandbox.
>
> For debugging with GDB we need the virtual address used by the process
> of the operating system as relocation target. This is in the range of
> the addresses assigned by calling mmap().
>
> gd->relocaddr is an address in the virtual address space of the sandbox.
> It is not an address in the memory space reserved by the mmap() call.
>

What I did for debugging sandbox u-boot, was:

$ gdb u-boot
>>> b do_pci

then type "pci" in the U-Boot shell, the breakpoint hits.

No relocation is needed. Are you doing something different?

> Here is an example:
>
> => bdinfo
> boot_params = 0x0000000000000000
> DRAM bank   = 0x0000000000000000
> -> start    = 0x0000000000000000
> -> size     = 0x0000000008000000
> relocaddr   = 0x0000000007e10000 // gd->relocaddr
> reloc off   = 0x00005557a047d000 // gd->reloc_off + gd->arch.ram_buf
> ethaddr     = 00:00:11:22:33:44
> IP addr     = 1.2.3.4
>
> For testing the sandbox here stipulates a virtual address space of
> [0x0-0x8000000]. But the addresses the CPU uses in the user process are
> 0x00005557a047c000 and above as shown by the pmap command:
>
> $ $ pmap 15398 | grep u-boot
> 15398:   ./u-boot
> 000055579047c000   1840K r-x-- u-boot
> 0000555790648000     28K r-x-- u-boot
> 000055579064f000    108K rwx-- u-boot
>

Regards,
Bin