[U-Boot] What is the expected meaning of CONFIG_SYS_NO_FLASH
Hi,
There is a bit of confusion at $dayjob about when CONFIG_SYS_NO_FLASH is used. Initially we thought that this meant I have no parallel NOR flash. So a board with only SPI flash would have CONFIG_SYS_NO_FLASH=1 and CONFIG_SPI_FLASH=1.
Is this understanding correct? I'd like to be able to add a blurb to README about how CONFIG_SYS_NO_FLASH should be used. Based on what I can tell from the code there seems to be a requirement that if !defined(CONFIG_SYS_NO_FLASH) something must implement flash_init(), flash_write(), etc as defined in include/flash.h. This could be a driver like cfi_flash.c or a board specific implementation.
Thanks, Chris
Hi Chris,
On 10.06.2015 02:02, Chris Packham wrote:
There is a bit of confusion at $dayjob about when CONFIG_SYS_NO_FLASH is used. Initially we thought that this meant I have no parallel NOR flash. So a board with only SPI flash would have CONFIG_SYS_NO_FLASH=1 and CONFIG_SPI_FLASH=1.
Is this understanding correct?
Yes. CONFIG_SYS_NO_FLASH dates back to a time when only parallel NOR flash (like CFI NOR) was available. And it definitely is now confusing at least. Perhaps it would be good to rename it to CONFIG_SYS_NO_PARALLEL_FLASH now.
I'd like to be able to add a blurb to README about how CONFIG_SYS_NO_FLASH should be used.
Thanks, that would be helpful.
Based on what I can tell from the code there seems to be a requirement that if !defined(CONFIG_SYS_NO_FLASH) something must implement flash_init(), flash_write(), etc as defined in include/flash.h. This could be a driver like cfi_flash.c or a board specific implementation.
Yes, this seems to be a correct assumption.
Thanks, Stefan
Unlike most configuration options defining this actually disables support for a feature (parallel flash). Eventually the logic behind this should probably be flipped so that '#ifndef CONFIG_SYS_NO_FLASH' becomes '#ifdef CONFIG_HAS_PARALLEL_FLASH' but for now lets document the existing behaviour.
Signed-off-by: Chris Packham judge.packham@gmail.com --- So this is my attempt to describe (my understanding of) how this option should be used. Any suggestions for improvement are most welcome.
README | 13 +++++++++++++ 1 file changed, 13 insertions(+)
diff --git a/README b/README index 3b406c2..c3fa549 100644 --- a/README +++ b/README @@ -3037,6 +3037,19 @@ CBFS (Coreboot Filesystem) support this is instead controlled by the value of /config/load-environment.
+- Parallel Flash support: + CONFIG_SYS_NO_FLASH + + Traditionally U-boot was run on systems with parallel NOR + flash. This option is used to disable support for parallel NOR + flash. This option should be defined if the board does not have + parallel flash. + + If this option is not defined one of the generic flash drivers + (e.g. CONFIG_FLASH_CFI_DRIVER or CONFIG_ST_SMI) must be + selected or the board must provide an implementation of the + flash API (see include/flash.h). + - DataFlash Support: CONFIG_HAS_DATAFLASH
On 10.06.2015 12:06, Chris Packham wrote:
Unlike most configuration options defining this actually disables support for a feature (parallel flash). Eventually the logic behind this should probably be flipped so that '#ifndef CONFIG_SYS_NO_FLASH' becomes '#ifdef CONFIG_HAS_PARALLEL_FLASH'
Yes, this should be the ultimate goal. But definitely a quite complex task.
but for now lets document the existing behaviour.
Ack.
Signed-off-by: Chris Packham judge.packham@gmail.com
Reviewed-by: Stefan Roese sr@denx.de
Thanks, Stefan
participants (3)
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Chris Packham -
Stefan Roese -
Stefan Roese