[U-Boot] Problem converting da850evm to generic board and use libfdt
Simon Glass
sjg at chromium.org
Thu Dec 11 01:49:27 CET 2014
Hi Peter,
On 10 December 2014 at 17:19, Peter Howard <pjh at northern-ridge.com.au> wrote:
> On Wed, 2014-12-10 at 15:43 -0700, Simon Glass wrote:
>> Hi Peter,
>>
>> On 10 December 2014 at 15:17, Peter Howard <pjh at northern-ridge.com.au> wrote:
>> >
>> > On Tue, 2014-12-09 at 17:45 -0700, Simon Glass wrote:
>> > > Hi Peter,
>> > >
>> > > On 9 December 2014 at 17:13, Peter Howard <pjh at northern-ridge.com.au> wrote:
>> > > >
>> > > > On Wed, 2014-12-03 at 14:20 -0800, Simon Glass wrote:
>> > > > > Hi Peter,
>> > > > >
>> > > > > On 3 December 2014 at 13:53, Peter Howard <pjh at northern-ridge.com.au> wrote:
>> > > > > > On Wed, 2014-12-03 at 06:38 -0700, Simon Glass wrote:
>> > > > > >> Hi Peter,
>> > > > > >>
>> > > > > >> On 2 December 2014 at 14:59, Peter Howard <pjh at northern-ridge.com.au> wrote:
>> > > > > >> >
>> > > > > >> > I'm trying to make two changes to building u-boot for the da850evm.
>> > > > > >> > * Use the generic board code to get rid of the warning, and
>> > > > > >> > * Enable libfdt to allow booting of linux with a standalone dtb
>> > > > > >> > image.
>> > > > > >> >
>> > > > > >> > The first part appears to be simple. Just adding
>> > > > > >> >
>> > > > > >> > #define CONFIG_SYS_GENERIC_BOARD
>> > > > > >> >
>> > > > > >> > in include/configs/da850evm.h works with no obvious side-effects.
>> > > > > >> >
>> > > > > >> > However, adding
>> > > > > >> >
>> > > > > >> > #define CONFIG_OF_LIBFDT
>> > > > > >> >
>> > > > > >> > is a different story. It appears to introduce memory corruption when
>> > > > > >> > loading the environment. On first boot it gives the "bad CRC!" warning
>> > > > > >> > and uses the default environment. If you *don't* save the environment
>> > > > > >> > you can boot fine (including manual editing of the environment). However
>> > > > > >> > if you save the environment via saveenv bad things happen on the next
>> > > > > >> > boot. An example log:
>> > > > > >> >
>> > > > > >> > U-Boot SPL 2015.01-rc1 (Nov 27 2014 - 14:30:26)
>> > > > > >> >
>> > > > > >> >
>> > > > > >> > U-Boot 2015.01-rc1 (Nov 27 2014 - 14:30:26)
>> > > > > >> >
>> > > > > >> > I2C: ready
>> > > > > >> > DRAM: 64 MiB
>> > > > > >> > WARNING: Caches not enabled
>> > > > > >> > MMC: davinci: 0
>> > > > > >> > SF: Detected M25P64 with page size 256 Bytes, erase size 64 KiB, total 8 MiB
>> > > > > >> > In: serial
>> > > > > >> > Out: serial
>> > > > > >> > Err: serial
>> > > > > >> > SF: Detected M25P64 with page size 256 Bytes, erase size 64 KiB, total 8 MiB
>> > > > > >> > Warning: Invalid MAC address read from SPI flash
>> > > > > >> > Net: DaVinci-EMAC
>> > > > > >> > Error: DaVinci-EMAC address not set.
>> > > > > >> >
>> > > > > >> > U-Boot > help
>> > > > > >> > data abort
>> > > > > >> > pc : [<c108ffd8>] lr : [<c10900b4>]
>> > > > > >> > sp : c3e5f838 ip : 00000000 fp : c3e5fda4
>> > > > > >> > r10: c10b1f28 r9 : c3e5ff08 r8 : 0000000e
>> > > > > >> > r7 : c10b22c4 r6 : c10aa2a0 r5 : 00000000 r4 : 0000001b
>> > > > > >> > r3 : c10b8f70 r2 : 00000001 r1 : c3e5f840 r0 : ffffffff
>> > > > > >> > Flags: Nzcv IRQs off FIQs off Mode SVC_32
>> > > > > >> > Resetting CPU ...
>> > > > > >> >
>> > > > > >> > If I rebuild with CONFIG_OF_LIBFDT removed again from da850evm.h the
>> > > > > >> > problem disappears. And you can see that the saveenv worked (i.e. the
>> > > > > >> > environment is what was saved before the reboot and data abort).
>> > > > > >> >
>> > > > > >> > I've traced the problem as far as the inline version of console_puts()
>> > > > > >> > in common/console.c. The table dispatch there and the fact that the
>> > > > > >> > problem appears only when you load the environment makes me think it's
>> > > > > >> > memory corruption.
>> > > > > >> >
>> > > > > >> > Note: if you do *not* specify CONFIG_SYS_GENERIC_BOARD you still get the
>> > > > > >> > data abort, however it takes a bit more effort to trigger (like actually
>> > > > > >> > looking at the environment :-) )
>> > > > > >> >
>> > > > > >> > (Note: This is building against the u-boot-2015.01-rc1 tree)
>> > > > > >> >
>> > > > > >> > Suggestions?
>> > > > > >>
>> > > > > >> In case it helps, I got the same symptom (help crashes) and it was due
>> > > > > >> to BSS not being cleared. Stefan (on cc) found this problem - he said
>> > > > > >> something to do with GDT calculation or handling. However it is just a
>> > > > > >> guess and probably has nothing to do with your issue.
>> > > > > >
>> > > > > > I may be missing something, but the GDT appears to be x86-specific
>> > > > > > whereas I'm building for ARMv5.
>> > > > >
>> > > > > OK for some reason I thought this was PPC!
>> > > > >
>> > > > > Maybe you can find your pc in System.map and work out where it is
>> > > > > going wrong? Are you hitting some image size limit?
>> > > > >
>> > > > > pc : [<c108ffd8>]
>> > > >
>> > > >
>> > > > Sorry, been distracted on other stuff for a few days.
>> > > >
>> > > > First, I now understand the global descriptor a bit better. For ARMv5
>> > > > It's stored in r9 and still looks sane. The relevant info:
>> > > >
>> > > > (gdb) print/x *((gd_t *)$r9)
>> > > > $1 = {bd = 0xc3e5ffb0, flags = 0x183, baudrate = 0x1c200, cpu_clk = 0x0,
>> > > > bus_clk = 0x0, pci_clk = 0x0, mem_clk = 0x0, have_console = 0x1,
>> > > > env_addr = 0xc10a8fcc, env_valid = 0x1, ram_top = 0xc4000000,
>> > > > relocaddr = 0xc3f80000, ram_size = 0x4000000, mon_len = 0x6ffb0,
>> > > > irq_sp = 0xc3e5fef0, start_addr_sp = 0xc3e5fee0, reloc_off = 0x2f00000,
>> > > > new_gd = 0xc3e5ff08, fdt_blob = 0x0, new_fdt = 0x0, fdt_size = 0x0,
>> > > > jt = 0xc3e601c0, env_buf = {0x31, 0x31, 0x35, 0x32, 0x30, 0x30,
>> > > > 0x0 <repeats 26 times>}, cur_i2c_bus = 0x0, timebase_h = 0x0,
>> > > > timebase_l = 0x0, arch = {timer_rate_hz = 0x16e360, tbu = 0x0,
>> > > > tbl = 0x4cc62, lastinc = 0x0, timer_reset_value = 0x0,
>> > > > tlb_addr = 0xc3ff0000, tlb_size = 0x4000}}
>> > > >
>> > > >
>> > > > The pc is definitely bogus. The reloc address is 0xc3f80000 whereas
>> > > > that would be a pre-reloc address (starting at 0xc1080000). And it's
>> > > > definitely relocated by the time of failure. The only other bit of
>> > > > information I have right now is that adding CONFIG_OF_LIBFDT drops the
>> > > > reloc address from 0xc3f85000 to 0xc3f80000.
>> > > >
>> > > > Don't know if any of that gives additional insight. Meanwhile I
>> > > > continue tracing.
>> > >
>> > > Yes, continue tracing.
>> > >
>> > > If ram_size is 0x40000000 and ram_top is 0xc4000000 then your RAM
>> > > presumably starts at 0xc0000000. Then the relocation address actually
>> > > seems reasonable to me.
>> > >
>> > > I don't know why the reloc address changes when you add CONFIG_OF_LIBFDT.
>> > >
>> > > You can add '#define DEBUG' at the very top of board_f/r.c to see addresses.
>> >
>> > I'm not sure what you meant by board_f/r.c as that file doesn't seem to
>>
>> common/board_f.c
>> common/board_r.c
>>
>> >
>> > exist. I whacked '#define DEBUG' in da850evm.h and got a wealth of
>> > output. However, the only new bit of information I've gleaned is that
>> > the lower that the reloc address goes, the faster things die. It goes
>> > lower in -rc3 (0xc3f7f000), and it doesn't make it to the prompt on a
>> > reset after saving the environment. Likewise with '#define DEBUG';
>> > after saving the environment it doesn't get back to the prompt on the
>> > next reset. All the addresses printed seem reasonable.
>> >
>> > The only thing that doesn't look right is that the command function
>> > pointers all look to be pre-reloc addresses. Though I don't see how
>> > this change would cause a failure that wouldn't happen already.
>> >
>> > So it seems that _something_ is being overwritten by the environment
>> > load, but I'm yet to get an idea of what.
>> >
>> > --
>> > Peter Howard <pjh at northern-ridge.com.au>
>> >
>>
>> Me neither. But you do have a data abort so may be able to look around
>> there and figure out where exactly it died. Better if you can use a
>> debugger.
>>
>
>
> Here's what appears to be happening with a death on typing
> "help" (-rc1): The logic flow gets to the (unrelocated) fputs() - and
> into the inline version of console_putc(). It looks up stdio_devices[1]
> (again, unrelocated addr) which is a valid pointer - sort of. The value
> is 0x2081004 which is outside of RAM, and the contents of the address
> are, according to gdb, zeroed out. Which means stdio_devices[1]->putc()
> is a jump to 0x0. I've stepped through that using JTAG+openocd+gdb.
>
> With extra debug statements, console output seems to cause a hang from
> somewhere in himport_r() (which is using relocated addresses including
> data).
>
> All this, to me, points to an issue with the unrelocated locations being
> used after environment import, but I don't know enough about u-boot
> structure to know if that is right or not . . .
>
>
> Peter Howard <pjh at northern-ridge.com.au>
>
Perhaps look at how it gets to the unrelocated fputs()? If it can call
the correct fputs() before initr_env() then you can perhaps narrow it
down.
But I can't see how you would be able to type at the console with this
problem, since fputs() is used by the command line editor.
I suspect you are actually seeing a symptom of something else. You
could try enabling CONFIG_CONSOLE_MUX and see if that changes the bug.
Regards,
Simon
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