On Wednesday, May 31, 2023 5:48 PM, Russell King (Oracle) wrote: > On Tue, May 30, 2023 at 04:40:36PM +0800, Jiawen Wu wrote: > > On Monday, May 29, 2023 10:06 AM, Jiawen Wu wrote: > > > On Friday, May 26, 2023 7:37 PM, Russell King (Oracle) wrote: > > > > On Fri, May 26, 2023 at 07:30:45PM +0800, kernel test robot wrote: > > > > > Kconfig warnings: (for reference only) > > > > > WARNING: unmet direct dependencies detected for I2C_DESIGNWARE_PLATFORM > > > > > Depends on [n]: I2C [=n] && HAS_IOMEM [=y] && (ACPI && COMMON_CLK [=y] || !ACPI) > > > > > Selected by [y]: > > > > > - TXGBE [=y] && NETDEVICES [=y] && ETHERNET [=y] && NET_VENDOR_WANGXUN [=y] && PCI [=y] > > > > > WARNING: unmet direct dependencies detected for SFP > > > > > Depends on [n]: NETDEVICES [=y] && PHYLIB [=y] && I2C [=n] && PHYLINK [=y] && (HWMON [=n] || HWMON [=n]=n) > > > > > Selected by [y]: > > > > > - TXGBE [=y] && NETDEVICES [=y] && ETHERNET [=y] && NET_VENDOR_WANGXUN [=y] && PCI [=y] > > > > > > > > ... and is basically caused by "select SFP". No. Do not do this unless > > > > you look at the dependencies for SFP and ensure that those are also > > > > satisfied - because if you don't you create messes like the above > > > > build errors. > > > > > > So how do I make sure that the module I need compiles and loads correctly, > > > rely on the user to manually select it? > > > > When I changed the TXGBE config to: > > ... > > depends on SFP > > select PCS_XPCS > > ... > > the compilation gave an error: > > > > drivers/net/phy/Kconfig:16:error: recursive dependency detected! > > drivers/net/phy/Kconfig:16: symbol PHYLIB is selected by PHYLINK > > drivers/net/phy/Kconfig:6: symbol PHYLINK is selected by PCS_XPCS > > drivers/net/pcs/Kconfig:8: symbol PCS_XPCS is selected by TXGBE > > drivers/net/ethernet/wangxun/Kconfig:40: symbol TXGBE depends on SFP > > drivers/net/phy/Kconfig:63: symbol SFP depends on PHYLIB > > For a resolution refer to Documentation/kbuild/kconfig-language.rst > > subsection "Kconfig recursive dependency limitations" > > > > Seems deleting "depends on SFP" is the correct way. But is this normal? > > How do we ensure the dependency between TXGBE and SFP? > > First, I would do this: > > select PHYLINK > select PCS_XPCS > > but then I'm principled, and I don't agree that PCS_XPCS should be > selecting PHYLINK. > > The second thing I don't particularly like is selecting user visible > symbols, but as I understand it, with TXGBE, the SFP slot is not an > optional feature, so there's little option. > > So, because SFP requires I2C: > > select I2C > select SFP > > That is basically what I meant by "you look at the dependencies for > SFP and ensure that those are also satisfied". > > Adding that "select I2C" also solves the unmet dependencies for > I2C_DESIGNWARE_PLATFORM. > > However, even with that, we're not done with the evilness of select, > because there's one more permitted configuration combination that > will break. > > If you build TXGBE into the kernel, that will force SFP=y, I2C=y, > PHYLINK=y, PHYLIB=y. So far so good. However, if HWMON=m, then things > will again break. So I would also suggest: > > select HWMON if TXGBE=y > > even though you don't require it, it solves the build fallout from > where HWMON=m but you force SFP=y. > > Maybe someone else has better ideas how to do this, but the above is > the best I can come up with. > > > IMHO, select is nothing but pure evil, and should be used with utmost > care and a full understanding of its ramifications, and a realisation > that it *totally* and *utterly* blows away any "depends on" on the > target of the select statement. > > An option that states that it depends on something else generally does > because... oddly enough, it _depends_ on that other option. So, if > select forces an option on without its dependencies, then it's not > surprising that stuff fails to build. > > Whenever a select statement is added, one must _always_ look at the > target symbol and consider any "depends on" there, and how to ensure > that those dependencies are guaranteed to always be satisfied. Thanks for the detailed explanation. I'll check each of the required options, and use "depends on" whenever possible.
