How to understand 'make oldconfig'?
Hi, I have tried to understand 'make oldconfig' command while configurating kernel. I do some experiments and get the following ideas: 1. When there is no a .config in /usr/src/linux, (1) If there is no a /boot/config-x.y.z, make will ask some questions and then produce a .config. (2) Otherwise, make will copy the /boot/config-x.y.z to /usr/src/linux/.config. My question: According to the messages generated by make, I get that both 'make defconfig' and 'make oldconfig' will gerenate .config based on 'i386_defconfig'. Why does 'make oldconfig' ask some questions, while 'make defconfig' does not? 2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old. My question: According to Love, "After making changes to your configuration file, or when using an existing configuration file on a new kernel tree, you can validate and update the configuration: make oldconfig." But, whether I edit .config and make some changes or I copy an existing .config into /usr/src/linux, 'make oldconfig' seems do nothing. So, how can I understand 'make oldconfig' in this case?
hi.... On Thu, Aug 25, 2011 at 23:32, Parmenides <mobile.parmenides@gmail.com> wrote:
Hi,
I have tried to understand 'make oldconfig' command while configurating kernel. I do some experiments and get the following ideas:
1. When there is no a .config in /usr/src/linux, (1) If there is no a /boot/config-x.y.z, make will ask some questions and then produce a .config. (2) Otherwise, make will copy the /boot/config-x.y.z to /usr/src/linux/.config.
My question: According to the messages generated by make, I get that both 'make defconfig' and 'make oldconfig' will gerenate .config based on 'i386_defconfig'. Why does 'make oldconfig' ask some questions, while 'make defconfig' does not?
because "make defconfig" is simply generating a default pre configured config file (it's based on i386_defconfig as you said). make oldconfig asks something? quite likely because you tried to fetch that config into newer kernel version. Thus, it asks your decision on what to do on those new introduced options.
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
I don't understand..... -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
I don't understand.....
Other 'make XXXconfig' such as: make config make menuconfig make xconfig make defconfig do some modification to the .config more or less. If 'make oldconfig' have not ask some questions, then the .config does not changed. So, I think the 'make oldconfig' does nothing. I wonder what 'make oldconfig' does. 2011/8/26 Mulyadi Santosa <mulyadi.santosa@gmail.com>:
hi....
On Thu, Aug 25, 2011 at 23:32, Parmenides <mobile.parmenides@gmail.com> wrote:
Hi,
I have tried to understand 'make oldconfig' command while configurating kernel. I do some experiments and get the following ideas:
1. When there is no a .config in /usr/src/linux, (1) If there is no a /boot/config-x.y.z, make will ask some questions and then produce a .config. (2) Otherwise, make will copy the /boot/config-x.y.z to /usr/src/linux/.config.
My question: According to the messages generated by make, I get that both 'make defconfig' and 'make oldconfig' will gerenate .config based on 'i386_defconfig'. Why does 'make oldconfig' ask some questions, while 'make defconfig' does not?
because "make defconfig" is simply generating a default pre configured config file (it's based on i386_defconfig as you said).
make oldconfig asks something? quite likely because you tried to fetch that config into newer kernel version. Thus, it asks your decision on what to do on those new introduced options.
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
I don't understand.....
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
On Fri, 26 Aug 2011 10:33:40 +0800 Parmenides <mobile.parmenides@gmail.com> wrote:
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
I don't understand.....
Other 'make XXXconfig' such as:
make config make menuconfig make xconfig make defconfig
do some modification to the .config more or less. If 'make oldconfig' have not ask some questions, then the .config does not changed. So, I think the 'make oldconfig' does nothing. I wonder what 'make oldconfig' does.
AFAIK, 'make oldconfig' is used to update your old .config file to the newer kernel. For exapmle, you have .config file of your current kernel and you downloaded new kernel and want to build your new kernel. Since very likely new kernel will have some new configuration options, you will need to update your config. Easiest way to do this is to run 'make oldconfig' which will ask you questions about new configuration options. (that is the ones your current .config file doesn't have)
2011/8/26 Mulyadi Santosa <mulyadi.santosa@gmail.com>:
hi....
On Thu, Aug 25, 2011 at 23:32, Parmenides <mobile.parmenides@gmail.com> wrote:
Hi,
I have tried to understand 'make oldconfig' command while configurating kernel. I do some experiments and get the following ideas:
1. When there is no a .config in /usr/src/linux, (1) If there is no a /boot/config-x.y.z, make will ask some questions and then produce a .config. (2) Otherwise, make will copy the /boot/config-x.y.z to /usr/src/linux/.config.
My question: According to the messages generated by make, I get that both 'make defconfig' and 'make oldconfig' will gerenate .config based on 'i386_defconfig'. Why does 'make oldconfig' ask some questions, while 'make defconfig' does not?
because "make defconfig" is simply generating a default pre configured config file (it's based on i386_defconfig as you said).
make oldconfig asks something? quite likely because you tried to fetch that config into newer kernel version. Thus, it asks your decision on what to do on those new introduced options.
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
I don't understand.....
-- regards,
Mulyadi Santosa Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com
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Leonid V. Fedorenchik
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
This book took all the mystery out of building the kernel for me http://www.kroah.com/lkn/ and I happily bought it because he was kind enough to give it away for free At my level - best kernel book ever - no more weird blank boot screens for some unknown reason when installing vanilla kernels. He actually posts here to. Adrian
Hi, On Thu, Aug 25, 2011 at 9:32 AM, Parmenides <mobile.parmenides@gmail.com> wrote:
Hi,
I have tried to understand 'make oldconfig' command while configurating kernel. I do some experiments and get the following ideas:
1. When there is no a .config in /usr/src/linux, (1) If there is no a /boot/config-x.y.z, make will ask some questions and then produce a .config. (2) Otherwise, make will copy the /boot/config-x.y.z to /usr/src/linux/.config.
My question: According to the messages generated by make, I get that both 'make defconfig' and 'make oldconfig' will gerenate .config based on 'i386_defconfig'. Why does 'make oldconfig' ask some questions, while 'make defconfig' does not?
Make defconfig takes the default configuration and copies it to .config. Make oldconfog takes the .config and runs it through the rules of the Kconfig files and produces a .config which is consistant with the Kconfig rules. If there are CONFIG values which are missing, the make oldconfig will ask for them. Simialrly if some option CONFIG_FOO is dependant on CONFIG_BAR, and CONFIG_BAR has been turned off, then make oldconfig will cause CONFIG_FOO to be turned off as well.
2. When there is a .config in /usr/src/linux indeed, make do nothing but generate a copy of .config, namely .config.old.
If the .config is already consistant with the rules found in Kconfig, then make oldconfig is essentially a no-op. If you were to run make oldconfig, and then run make oldconfig a second time, the second time won't cause any additional changes to be made.
My question: According to Love, "After making changes to your configuration file, or when using an existing configuration file on a new kernel tree, you can validate and update the configuration: make oldconfig." But, whether I edit .config and make some changes or I copy an existing .config into /usr/src/linux, 'make oldconfig' seems do nothing. So, how can I understand 'make oldconfig' in this case?
If make oldconfig does nothing, it just means that the .config doesn't have any inconsistencies in it. -- Dave Hylands Shuswap, BC, Canada http://www.davehylands.com
participants (5)
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Adrian Cornish -
Dave Hylands -
Leonid V. Fedorenchik -
Mulyadi Santosa -
Parmenides