[U-Boot] Problem converting da850evm to generic board and use libfdt
Peter Howard
pjh at northern-ridge.com.au
Wed Dec 17 00:21:54 CET 2014
On Tue, 2014-12-16 at 17:27 +1100, Peter Howard wrote:
> On Wed, 2014-12-10 at 19:10 -0700, Simon Glass wrote:
> > Hi Peter,
> >
> > On 10 December 2014 at 18:37, Simon Glass <sjg at chromium.org> wrote:
> > > Hi Peter,
> > >
> > > On Dec 10, 2014 6:23 PM, "Peter Howard" <pjh at northern-ridge.com.au> wrote:
> > >>
> > >> On Wed, 2014-12-10 at 17:49 -0700, Simon Glass wrote:
> > >> > 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.
> > >>
> > >> Hmmm. That produces a new failure - it goes into an endless loop in
> > >> fgetc(). And it does that:
> > >> * With CONFIG_GENERIC_BOARD and CONFIG_OF_LIBFDT - both with and
> > >> without saving the environment
> > >> * With CONFIG_GENERIC_BOARD only,
> > >> * Without CONFIG_GENERIC_BOARD.
> > >>
> > >> :-)
> > >
> > > so just adding the console config changes the behavior on your board? Does
> > > you BSS work? Do you have a custom link script? Are you writing to BSS
> > > before relocation?
> >
> > I see a few things:
> >
> > - 4KB stack (should be enough I suppose)
> > - SPL link script, but it doesn't look like it does anything useful.
> > Maybe drop it?
> >
> > But I'm pretty sure this is nothing to do with it. This is a bit of a
> > long shot, but if your relocation is broken you might be corrupting
> > BSS - the variables in System.map between __rel_dyn_start and
> > __rel_dyn_end. This can happen if you write to a BSS variable before
> > relocation. You can check the area (e.g. by checksumming it) early in
> > board_init_f() - e.g. setup_mon_len(). Put the result in a new member
> > of struct global_data (gd) - then checksum again and compare before
> > relocation in setup_reloc().
> >
> > Probably nothing else but to keep digging.
>
> OK, I _think_ I have a handle on this. But hopefully there's someone
> out there who understands better than me how the da850 SPI flash is
> setup wrt. u-boot usage.
>
> It appears that the damage occurs with the actual writing of the env via
> saveenv (i.e. not the reading back of it next time round). Why?
> because stepping through crt0.S and relocate.S shows different results
> by relocate_done: in relocate.S When the environment is not read, all
> the relocations are correct. After saveenv is done and the board is
> reset, various relocations are incomplete - i.e. the addresses in the
> relocated tables point to the pre-relocation addresses. Which then get
> trashed when the environment is read (afterwards).
>
> I'm guessing that the problem is the size of the u-boot image is now
> overlapping in spi flash with the location of the environment. So
> saving the environment actually trashes part of the u-boot image.
> Further guessing is it involves the __rel_dyn area, so the address
> fixups don't happen.
>
> Does that sound believable?
And yes, that _was_ the problem. After all that, a 2 line fix (apart
from the enabling of the generic platform and libfdt). Patch to follow.
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