[PATCH v2] xyz-modem: Select CRC16

[Quentin Schulz]

On 6/8/26 4:04 PM, Tom Rini wrote:
> On Mon, Jun 08, 2026 at 03:59:11PM +0200, Quentin Schulz wrote:
>> Hi Daniel,
>>
>> On 6/8/26 3:06 PM, Daniel Palmer wrote:
>>> - CONFIG_LOADB causes the xyzModem code to get built and that code depends
>>>     on CONFIG_CRC16. If you don't have something else that selects CONFIG_CRC16
>>>     you can unselect it and then the final link will fail:
>>>
>>>     LD      u-boot
>>> /usr/bin/m68k-linux-gnu-ld.bfd: common/xyzModem.o: in function `xyzModem_get_hdr':
>>> u-boot/common/xyzModem.c:388:(.text.xyzModem_get_hdr+0x17a): undefined reference to `crc16_ccitt'
>>>
>>> - Add CONFIG_YMODEM_SUPPORT, make that select CONFIG_CRC16 and make
>>>     CONFIG_LOADB select CONFIG_YMODEM_SUPPORT.
>>>
>>> - SPL/TPL already have Kconfig symbols for ymodem support but the spl
>>>     ymodem code has issues building in the TPL phase and doesn't seem to
>>>     be used:
>>>
>>> /usr/bin/aarch64-linux-gnu-ld.bfd: common/spl/spl_ymodem.o: in function `spl_ymodem_load_image':
>>> u-boot/common/spl/spl_ymodem.c:138:(.text.spl_ymodem_load_image+0xdc): undefined reference to `spl_load_simple_fit'
>>> u-boot/common/spl/spl_ymodem.c:138:(.text.spl_ymodem_load_image+0xdc): relocation truncated to fit: R_AARCH64_CALL26 against undefined symbol `spl_load_simple_fit'
>>> make[1]: *** [scripts/Makefile.xpl:546: tpl/u-boot-tpl] Error 1
>>>
>>> - Remove the ymodem symbol entirely for TPL.
>>>
>>> - Select CONFIG_SPL_CRC16 for SPL.
>>>
>>> - Finally, since everyone is now using the ymodem support symbols remove
>>>     the special rule for loadb in the makefile.
>>>
>>
>> When you need to list what you're doing in a commit log, it usually means
>> you should be splitting the content into multiple separate patches (in a
>> single series is usually fine/recommended).
>>
>> What I could identify (slightly reworked, which better match how *I* would
>> write the patches):
>>
>> - changes made to common/spl/Kconfig.tpl with the justification given above,

And I also see a mention of CONFIG_TPL_YMODEM_SUPPORT=y in 
doc/usage/spl_boot.rst that would need removal

>> - adding the missing CRC16 dependency to CMD_LOADB,
>> - adding missing SPL_CRC16 dependency to SPL_YMODEM_SUPPORT (possibly
>> squashed with the CMD_LOADB+CRC16 patch above, I'm undecided on what's best
>> here),
>> - create new YMODEM_SUPPORT symbol and migrate CMD_LOADB + common/Makefile
>> to use that,
>>
>> This makes it clearer what the purpose of each individual commit is:
>> - remove dead code
>> - fix existing support for CMD_LOADB,
>> - fix existing support for SPL_YMODEM_SUPPORT,
>> - quality of life improvement by migrating the CRC16 dependency from
>> CMD_LOADB into a new symbol + making use of that new symbol in
>> common/Makefile instead of "hardlinking" CMD_LOADB with building xyzModem.o
>> (which is quite honestly confusing, so good to see this fixed!),
>>
>> What do you think?
>>
>>> Signed-off-by: Daniel Palmer <daniel at thingy.jp>
>>> ---
>>>
>>> v2: Fix the SPL/TPL stuff as brought up by Tom. This opened a can of
>>>       worms when I tested if the TPL builds or not so I decided to just
>>>       remove the TPL ymodem stuff. It didn't seem to be used in any
>>>       defconfig and there isn't a CONFIG_TPL_CRC16 to enable the needed
>>>       crc16 code anyhow so maybe it hasn't been used for a while?
>>>
>>>    cmd/Kconfig            |  1 +
>>>    common/Kconfig         |  4 ++++
>>>    common/Makefile        |  1 -
>>>    common/spl/Kconfig     |  1 +
>>>    common/spl/Kconfig.tpl | 11 +----------
>>>    5 files changed, 7 insertions(+), 11 deletions(-)
>>>
>>> diff --git a/cmd/Kconfig b/cmd/Kconfig
>>> index c71c6824a196..503fc51f6bb4 100644
>>> --- a/cmd/Kconfig
>>> +++ b/cmd/Kconfig
>>> @@ -1412,6 +1412,7 @@ config CMD_W1
>>>    config CMD_LOADB
>>>    	bool "loadb"
>>>    	default y
>>> +	select YMODEM_SUPPORT
>>>    	help
>>>    	  Load a binary file over serial line.
>>> diff --git a/common/Kconfig b/common/Kconfig
>>> index 8e8c733aa295..0db74aa580e4 100644
>>> --- a/common/Kconfig
>>> +++ b/common/Kconfig
>>> @@ -1274,3 +1274,7 @@ config IO_TRACE
>>>    	  confirm that the driver behaves the same way before and after a code
>>>    	  change. To add support for your architecture, add '#include
>>>    	  <iotrace.h>' to the bottom of arch/<arch>/include/asm/io.h and test.
>>> +
>>> +config YMODEM_SUPPORT
>>> +	bool
>>> +	select CRC16
>>
>> Is there any reason we wouldn't want the user to be able to select this
>> independently from CMD_LOADB?
>>
>> I'm asking because this is both invisible (no prompt) and has no help text.
> 
> I think this should stay hidden as it's *not* hidden for xPL as it's the
> equivalent of CMD_LOADB but it's the symbol for the library portion. As
> a maybe clearer result, maybe the library symbol should be
> XYZMODEM_SUPPORT / xPL_XYZMODEM_SUPPORT, to control building
> common/xyzModem.o ?
> 

I'm not sure to understand how the rename would help here? I'm assuming 
we have an issue of the symbol having a different meaning in xPL and in 
proper. If I understood correctly, YMODEM_SUPPORT in proper is for 
building the library and using it, while in xPL it's both for building 
the library and add support for loading the next U-Boot stage over UART. 
Is this what you meant? Are you suggesting we split "build library code" 
and "load next stage from UART" into separate symbols?

Also, lib/Makefile has

obj-$(CONFIG_SPL_YMODEM_SUPPORT) += crc16-ccitt.o

which is.... odd? Shouldn't this handle the case of "missing" SPL_CRC16 
dependency? So: does it really not build if SPL_CRC16=n but 
SPL_YMODEM_SUPPORT=y? If it does not build, is bringing SPL_CRC16 too 
much? We only need crc16-ccitt.o I think, and this will also bring 
crc16.o into the SPL, which may not be desired (size increase).

Cheers,
Quentin