Messages in this thread | | | Subject | Re: [PATCH v2 3/7] powerpc: convert config files to generic cmdline | From | Christophe Leroy <> | Date | Wed, 24 Mar 2021 17:59:59 +0100 |
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Le 09/03/2021 à 22:29, Daniel Walker a écrit : > On Tue, Mar 09, 2021 at 08:47:09AM +0100, Christophe Leroy wrote: >> >> >> Le 09/03/2021 à 01:02, Daniel Walker a écrit : >>> This is a scripted mass convert of the config files to use >>> the new generic cmdline. There is a bit of a trim effect here. >>> It would seems that some of the config haven't been trimmed in >>> a while. >> >> If you do that in a separate patch, you loose bisectability. >> >> I think it would have been better to do things in a different way, more or less like I did in my series: >> 1/ Provide GENERIC cmdline at the same functionnality level as what is >> spread in the different architectures >> 2/ Convert architectures to the generic with least churn. >> 3/ Add new features to the generic > > You have to have the churn eventually, no matter how you do it. The only way you > don't have churn is if you never upgrade the feature set. > > >>> >>> The bash script used to convert is as follows, >>> >>> if [[ -z "$1" || -z "$2" ]]; then >>> echo "Two arguments are needed." >>> exit 1 >>> fi >>> mkdir $1 >>> cp $2 $1/.config >>> sed -i 's/CONFIG_CMDLINE=/CONFIG_CMDLINE_BOOL=y\nCONFIG_CMDLINE_PREPEND=/g' $1/.config >> >> This is not correct. >> >> By default, on powerpc the provided command line is used only if the bootloader doesn't provide one. >> >> Otherwise: >> - the builtin command line is appended to the one provided by the bootloader >> if CONFIG_CMDLINE_EXTEND is selected >> - the builtin command line replaces to the one provided by the bootloader if >> CONFIG_CMDLINE_FORCE is selected > > I think my changes maintain most of this due to the override of > CONFIG_CMDLINE_PREPEND. This is an upgrade and the inflexibility in powerpc is > an example of why these changes were created in the first place.
"inflexibility in powerpc" : Can you elaborate ?
> > For example , say the default command line is "root=/dev/issblk0" from iss476 > platform. And the bootloader adds "root=/dev/sda1" > > The result is <prepend><bootloader><append>.
I'm still having hard time understanding the benefit of having both <prepend> and <append>. Could you please provide a complete exemple from real life, ie what exactly the problem is and what it solves ?
> > Then you have, > > root=/dev/issblk0 root=/dev/sda1 > > and the bootloader has precedent over the default command line. So root= in the > above cases is defined by the bootloader. > > The only issue would be if a person wants to override the default command line > with an unrelated bootloader command line. I don't know how many people do this, > but I doubt it's many. Can you think of any use cases like this? > > I would imagine there are many more people who have to entirely duplicate the > default command line in the boot loader when they really just want to change a > single part of it like the root= device or console device or speed. > > Daniel >
Christophe
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