Re: Cross Compiling a different architechture
On Wed, Jan 9, 2013 at 3:30 AM, Ganesh B ganeshsu...@yahoo.com wrote: I do not know why but whether ncurses or menuconfig the build fails at some modules (specially hardware architecture ones), specially at cross compiling architecture build stage. It went smoothly for same system architecture like i386 or x86 but not for arm or arm64. Where is the doc's for Kernel defconfig and kconfig in Kernel.org? I am trying to make and edit each manually for each architecture and then run make all. The problem is it is not allowing me to assemble all sub-architectures for say arm or arm64 as a dynamic module. I have to specify and select each option (sub-hardware architecture) specifically during build of defconfig for the architecture. My x86 is also blocking the build at times. I did not get anything good on my google search. I would say a wiser choice would be getting a .config from somewhere and editing options which you really need to change. I am not sure if you understand this or not, but you need to have a series of toolchains for each arch you need to cross compile at different locations. For different binaries of different arch, I would suggest you use different directories of same source code. Generally make clean or distclean should get rid of most binaries, but starting a clean build is always the best idea. Toolchains can be bit of a pain to get right. w.r.t. Knoppix, Thank you, let me check the informit link for the architecture and usage relevance. TnR, Ganesh -- *From:* Anuz Pratap Singh Tomar chambilketha...@gmail.com *To:* Ganesh B ganeshsu...@yahoo.com *Cc:* Mulyadi Santosa mulyadi.sant...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org *Sent:* Tuesday, January 8, 2013 8:44 PM *Subject:* Re: Cross Compiling a different architechture On Tue, Jan 8, 2013 at 2:39 PM, Ganesh B ganeshsu...@yahoo.com wrote: Creating Defconfig and menuconfig (options) for all in one system from kernel. I want a clean build rather than an external mount, most I found did not have documentation. there is extensive documentation under Documentation/ directory in kernel source. on simple search I got this link about building kernel on knoppix: http://www.informit.com/articles/article.aspx?p=422949seqNum=3 pretty much on most distribution, you can install ncurses and go for make menuconfig and then just make(i.e. if you are native compiling the kernel). However the config for distributions are fairly complex these days, so you may require to build few other things like initrd and create devices files and all. Please refer to distro documentation for knoppix: http://knoppix.net/wiki/Main_Page I would recommend that you read these guidelines before asking any question on this list http://kernelnewbies.org/mailinglistguidelines TnR, Ganesh -- *From:* Mulyadi Santosa mulyadi.sant...@gmail.com *To:* Ganesh B ganeshsu...@yahoo.com *Cc:* Anuz Pratap Singh Tomar chambilketha...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org *Sent:* Tuesday, January 8, 2013 9:18 AM *Subject:* Re: Cross Compiling a different architechture Hi On Tue, Jan 8, 2013 at 10:36 AM, Ganesh B ganeshsu...@yahoo.com wrote: Hello, Any help with some doc's. I see a defconfig for all, but the tree is not clear. Any documentation support for this in .Kconfig and .defconfig? Which config option you're not clear? Asking like this will only put you in the blue, you know -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- Thank you Warm Regards Anuz -- Thank you Warm Regards Anuz ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cross Compiling a different architechture
Okay makes sense let me try clean before building different arch. I am not doing this at the moment. Would I need to have different toolchains for same architecture, I was trying to build for all processor types for an arch using a different toolchain but it failed? Ones that passed the different cross-compile arch failed at some modules speciially the net, sound, video, or built_in sections. Let me check this and revert. Have you ever compiled a complete end to end allyesconfig for a same or cross-compile build? allyesconfig gave me dependency/ missing/ invalid entry errors for cross-compile arch like arm. TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 11:19 AM Subject: Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 3:30 AM, Ganesh B ganeshsu...@yahoo.com wrote: I do not know why but whether ncurses or menuconfig the build fails at some modules (specially hardware architecture ones), specially at cross compiling architecture build stage. It went smoothly for same system architecture like i386 or x86 but not for arm or arm64. Where is the doc's for Kernel defconfig and kconfig in Kernel.org? I am trying to make and edit each manually for each architecture and then run make all. The problem is it is not allowing me to assemble all sub-architectures for say arm or arm64 as a dynamic module. I have to specify and select each option (sub-hardware architecture) specifically during build of defconfig for the architecture. My x86 is also blocking the build at times. I did not get anything good on my google search. I would say a wiser choice would be getting a .config from somewhere and editing options which you really need to change. I am not sure if you understand this or not, but you need to have a series of toolchains for each arch you need to cross compile at different locations. For different binaries of different arch, I would suggest you use different directories of same source code. Generally make clean or distclean should get rid of most binaries, but starting a clean build is always the best idea. Toolchains can be bit of a pain to get right. w.r.t. Knoppix, Thank you, let me check the informit link for the architecture and usage relevance. TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: Mulyadi Santosa mulyadi.sant...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Tuesday, January 8, 2013 8:44 PM Subject: Re: Cross Compiling a different architechture On Tue, Jan 8, 2013 at 2:39 PM, Ganesh B ganeshsu...@yahoo.com wrote: Creating Defconfig and menuconfig (options) for all in one system from kernel. I want a clean build rather than an external mount, most I found did not have documentation. there is extensive documentation under Documentation/ directory in kernel source. on simple search I got this link about building kernel on knoppix: http://www.informit.com/articles/article.aspx?p=422949seqNum=3 pretty much on most distribution, you can install ncurses and go for make menuconfig and then just make(i.e. if you are native compiling the kernel). However the config for distributions are fairly complex these days, so you may require to build few other things like initrd and create devices files and all. Please refer to distro documentation for knoppix: http://knoppix.net/wiki/Main_Page I would recommend that you read these guidelines before asking any question on this list http://kernelnewbies.org/mailinglistguidelines TnR, Ganesh From: Mulyadi Santosa mulyadi.sant...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: Anuz Pratap Singh Tomar chambilketha...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Tuesday, January 8, 2013 9:18 AM Subject: Re: Cross Compiling a different architechture Hi On Tue, Jan 8, 2013 at 10:36 AM, Ganesh B ganeshsu...@yahoo.com wrote: Hello, Any help with some doc's. I see a defconfig for all, but the tree is not clear. Any documentation support for this in .Kconfig and .defconfig? Which config option you're not clear? Asking like this will only put you in the blue, you know -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- Thank you Warm Regards Anuz -- Thank you Warm Regards Anuz___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org
Re: Cross Compiling a different architechture
On Wed, Jan 9, 2013 at 12:06 PM, Ganesh B ganeshsu...@yahoo.com wrote: Okay makes sense let me try clean before building different arch. I am not doing this at the moment. Would I need to have different toolchains for same architecture, I was trying to build for all processor types for an arch using a different toolchain but it failed? You _may_ require different toolchains for different processor with same arch types, for example under x86, i386 and i586 toolchains _may_ be used interchangably but not ia64 or x86_64 or may not even for atom. Similarly in ARM, there are different families of processor and there may be big endian or small endian processor. So you may have to find the correct toolchain for the given config. Ones that passed the different cross-compile arch failed at some modules speciially the net, sound, video, or built_in sections. Let me check this and revert. Have you ever compiled a complete end to end allyesconfig for a same or cross-compile build? allyesconfig gave me dependency/ missing/ invalid entry errors for cross-compile arch like arm. Why would you do enable all config options? There may be incompatible dependencies, which will ofcourse lead to compilation errors. I generally get .config files from elsewhere, sometimes there are files inside the source somewhere or sometimes you just do make ARCH=XXX menuconfig and then configure the options selectively. I may try to build toolchain for raspberry pi in few days and see if I face such issues or not(but that is highly tentative. ) TnR, Ganesh -- *From:* Anuz Pratap Singh Tomar chambilketha...@gmail.com *To:* Ganesh B ganeshsu...@yahoo.com *Cc:* kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org *Sent:* Wednesday, January 9, 2013 11:19 AM *Subject:* Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 3:30 AM, Ganesh B ganeshsu...@yahoo.com wrote: I do not know why but whether ncurses or menuconfig the build fails at some modules (specially hardware architecture ones), specially at cross compiling architecture build stage. It went smoothly for same system architecture like i386 or x86 but not for arm or arm64. Where is the doc's for Kernel defconfig and kconfig in Kernel.orghttp://kernel.org/? I am trying to make and edit each manually for each architecture and then run make all. The problem is it is not allowing me to assemble all sub-architectures for say arm or arm64 as a dynamic module. I have to specify and select each option (sub-hardware architecture) specifically during build of defconfig for the architecture. My x86 is also blocking the build at times. I did not get anything good on my google search. I would say a wiser choice would be getting a .config from somewhere and editing options which you really need to change. I am not sure if you understand this or not, but you need to have a series of toolchains for each arch you need to cross compile at different locations. For different binaries of different arch, I would suggest you use different directories of same source code. Generally make clean or distclean should get rid of most binaries, but starting a clean build is always the best idea. Toolchains can be bit of a pain to get right. w.r.t. Knoppix, Thank you, let me check the informit link for the architecture and usage relevance. TnR, Ganesh -- *From:* Anuz Pratap Singh Tomar chambilketha...@gmail.com *To:* Ganesh B ganeshsu...@yahoo.com *Cc:* Mulyadi Santosa mulyadi.sant...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org *Sent:* Tuesday, January 8, 2013 8:44 PM *Subject:* Re: Cross Compiling a different architechture On Tue, Jan 8, 2013 at 2:39 PM, Ganesh B ganeshsu...@yahoo.com wrote: Creating Defconfig and menuconfig (options) for all in one system from kernel. I want a clean build rather than an external mount, most I found did not have documentation. there is extensive documentation under Documentation/ directory in kernel source. on simple search I got this link about building kernel on knoppix: http://www.informit.com/articles/article.aspx?p=422949seqNum=3 pretty much on most distribution, you can install ncurses and go for make menuconfig and then just make(i.e. if you are native compiling the kernel). However the config for distributions are fairly complex these days, so you may require to build few other things like initrd and create devices files and all. Please refer to distro documentation for knoppix: http://knoppix.net/wiki/Main_Page I would recommend that you read these guidelines before asking any question on this list http://kernelnewbies.org/mailinglistguidelines TnR, Ganesh -- *From:* Mulyadi Santosa mulyadi.sant...@gmail.com *To:* Ganesh B ganeshsu...@yahoo.com *Cc:* Anuz Pratap Singh Tomar chambilketha...@gmail.com;
Re: Cross Compiling a different architechture
Yes, you touch the pain area I am facing. I could build x86 as well as i386 toolchain. Though I have not tried the image yet. But when cross compiling arm and arm64 say for example, I receive .config related errors which either does not create the .config or gives errors like I mentioned. Would I be able to do a allyesconfig for this? If yes, what options needs to be missed or edited to get the processor selection at runtime. using i386 machine $make ARCH=arm defconfig - ends up with errors of hardware conpatibility of i386, .config not created $make ARCH=arm allyesconfig - ends up with errors of hardware conpatibility specially sub-architecture of processor, .config not created $make ARCH=arm menuconfig - all options enabled gives while building, .config created but kernel not built while using make TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 12:20 PM Subject: Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 12:06 PM, Ganesh B ganeshsu...@yahoo.com wrote: Okay makes sense let me try clean before building different arch. I am not doing this at the moment. Would I need to have different toolchains for same architecture, I was trying to build for all processor types for an arch using a different toolchain but it failed? You _may_ require different toolchains for different processor with same arch types, for example under x86, i386 and i586 toolchains _may_ be used interchangably but not ia64 or x86_64 or may not even for atom. Similarly in ARM, there are different families of processor and there may be big endian or small endian processor. So you may have to find the correct toolchain for the given config. Ones that passed the different cross-compile arch failed at some modules speciially the net, sound, video, or built_in sections. Let me check this and revert. Have you ever compiled a complete end to end allyesconfig for a same or cross-compile build? allyesconfig gave me dependency/ missing/ invalid entry errors for cross-compile arch like arm. Why would you do enable all config options? There may be incompatible dependencies, which will ofcourse lead to compilation errors. I generally get .config files from elsewhere, sometimes there are files inside the source somewhere or sometimes you just do make ARCH=XXX menuconfig and then configure the options selectively. I may try to build toolchain for raspberry pi in few days and see if I face such issues or not(but that is highly tentative. ) TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 11:19 AM Subject: Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 3:30 AM, Ganesh B ganeshsu...@yahoo.com wrote: I do not know why but whether ncurses or menuconfig the build fails at some modules (specially hardware architecture ones), specially at cross compiling architecture build stage. It went smoothly for same system architecture like i386 or x86 but not for arm or arm64. Where is the doc's for Kernel defconfig and kconfig in Kernel.org? I am trying to make and edit each manually for each architecture and then run make all. The problem is it is not allowing me to assemble all sub-architectures for say arm or arm64 as a dynamic module. I have to specify and select each option (sub-hardware architecture) specifically during build of defconfig for the architecture. My x86 is also blocking the build at times. I did not get anything good on my google search. I would say a wiser choice would be getting a .config from somewhere and editing options which you really need to change. I am not sure if you understand this or not, but you need to have a series of toolchains for each arch you need to cross compile at different locations. For different binaries of different arch, I would suggest you use different directories of same source code. Generally make clean or distclean should get rid of most binaries, but starting a clean build is always the best idea. Toolchains can be bit of a pain to get right. w.r.t. Knoppix, Thank you, let me check the informit link for the architecture and usage relevance. TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: Mulyadi Santosa mulyadi.sant...@gmail.com; kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Tuesday, January 8, 2013 8:44 PM Subject: Re: Cross Compiling a different architechture On Tue, Jan 8, 2013 at 2:39 PM, Ganesh B ganeshsu...@yahoo.com wrote: Creating Defconfig and menuconfig (options)
Re: /usr/ld Not enough room for program headers
On Wed, Jan 09, 2013 at 08:51:36PM +0800, Peter Teoh wrote:
On Wed, Jan 9, 2013 at 6:36 AM, horseriver horseriv...@gmail.com wrote:
On Wed, Jan 09, 2013 at 01:28:12PM +0800, Peter Teoh wrote:
On Sun, Jan 6, 2013 at 11:17 AM, horseriver horseriv...@gmail.com
wrote:
VSYSCALL_BASE = 0xe000;
SECTIONS
{
. = VSYSCALL_BASE ;
.hash : { *(.hash) }:text
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version: { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
I suspect something wrong with VSYSCALL_BASE + value here.
look at this:
http://marcbug.scc-dc.com/svn/repository/trunk/linuxkernel/linux-2.6.16-mcemu/arch/x86_64/ia32/vsyscall.lds
and doing a diff with your ld script, there is not much diff, except for
the VSYSCALL_BASE + SIZEOF_HEADER
thanks!
I do not understand what this error /usr/ld Not enough room for program
headers really mean ?
if I add SIZEOF_HEADER , this error is still reproted ,
when ld link files , does it only need a ld-script file ? or more than one
ld-script files ?
portion.
Read here to understand how SIZEOF_HEADER is calculated:
http://www.math.utah.edu/docs/info/ld_3.html#SEC13
Not sure why do u want to shift the whole section by SIZEOF_HEADER down in
bytes?
--
Regards,
Peter Teoh
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Re: Kernelnewbies Digest, Vol 26, Issue 24
Peter,
This was the best. I was struggling to find this. Thank you.
TnR,
Ganesh
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To: kernelnewbies@kernelnewbies.org
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Today's Topics:
1. Linux Kernel Map (Peter Teoh)
2. Re: /usr/ld Not enough room for program headers (horseriver)
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Message: 1
Date: Wed, 9 Jan 2013 21:25:11 +0800
From: Peter Teoh htmldevelo...@gmail.com
Subject: Linux Kernel Map
To: kernelnewbies@kernelnewbies.org
kernelnewbies@kernelnewbies.org
Message-ID:
CAHnt0GVj=t-e39dlvcyxbl2o48ejzotemquftkk4dkxzrig...@mail.gmail.com
Content-Type: text/plain; charset=iso-8859-1
http://www.makelinux.net/kernel_map/
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Regards,
Peter Teoh
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Date: Wed, 9 Jan 2013 12:56:51 +0800
From: horseriver horseriv...@gmail.com
Subject: Re: /usr/ld Not enough room for program headers
To: Peter Teoh htmldevelo...@gmail.com
Cc: kernelnewbies@kernelnewbies.org
Message-ID: 20130109045651.GB3236@debian.localdomain
Content-Type: text/plain; charset=us-ascii
On Wed, Jan 09, 2013 at 08:51:36PM +0800, Peter Teoh wrote:
On Wed, Jan 9, 2013 at 6:36 AM, horseriver horseriv...@gmail.com wrote:
On Wed, Jan 09, 2013 at 01:28:12PM +0800, Peter Teoh wrote:
On Sun, Jan 6, 2013 at 11:17 AM, horseriver horseriv...@gmail.com
wrote:
VSYSCALL_BASE = 0xe000;
SECTIONS
{
. = VSYSCALL_BASE ;
.hash : { *(.hash) } :text
.dynsym : { *(.dynsym) }
.dynstr : { *(.dynstr) }
.gnu.version : { *(.gnu.version) }
.gnu.version_d : { *(.gnu.version_d) }
.gnu.version_r : { *(.gnu.version_r) }
I suspect something wrong with VSYSCALL_BASE + value here.
look at this:
http://marcbug.scc-dc.com/svn/repository/trunk/linuxkernel/linux-2.6.16-mcemu/arch/x86_64/ia32/vsyscall.lds
and doing a diff with your ld script, there is not much diff, except for
the VSYSCALL_BASE + SIZEOF_HEADER
thanks!
I do not understand what this error /usr/ld Not enough room for program
headers really mean ?
if I add SIZEOF_HEADER , this error is still reproted ,
when ld link files , does it only need a ld-script file ? or more than one
ld-script files ?
portion.
Read here to understand how SIZEOF_HEADER is calculated:
http://www.math.utah.edu/docs/info/ld_3.html#SEC13
Not sure why do u want to shift the whole section by SIZEOF_HEADER down in
bytes?
--
Regards,
Peter Teoh
--
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End of Kernelnewbies Digest, Vol 26, Issue 24
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Re: Linux Kernel Map
On Wed, Jan 9, 2013 at 2:25 PM, Peter Teoh htmldevelo...@gmail.com wrote: http://www.makelinux.net/kernel_map/ This map is horrible outdated. I see lock_kernel() for example... -- Thanks, //richard ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: why are scheduling domains used in multiprocessor systems
On Wed, Jan 9, 2013 at 4:03 PM, Bond jamesbond.2...@gmail.com wrote: Hi, please see this question http://stackoverflow.com/questions/14229793/what-does-struct-sched-domain-stands-for-in-include-linux-sched-h-scheduling-do I checked following http://lwn.net/Articles/169277/ and following http://www.kernel.org/doc/Documentation/scheduler/sched-domains.txt the first line of kernel.org doc says . Each CPU has a base scheduling domain (struct sched_domain).. and second para says each scheduling domain spans a number of CPUs (stored in the -span field). third para says Each scheduling domain must have one or more CPU groups.. The intersection of cpumasks from any two of these groups MUST be the empty set. then some where in doc it says Balancing within a sched domain occurs between groups. That is, each group is treated as one entity. the doc in details talks about the implementation of scheduling domains and mentions that CPUs should belong to one of the scheduling domain in a way that cpumasks intersection should be an empty set The answer of the question that I want to know is why is a scheduling domain actually needed? _ CPU scheduling involving many configuration and factors. https://www.cs.unm.edu/~eschulte/classes/cs587/data/10.1.1.59.6385.pdf Goto page 18 for definition of scheduler domain, and it says: Each node in a system has a scheduler domain that points to its parent scheduler domain. A node might be a uniprocessor system, an SMP system, or a node within a NUMA system. this complex hierarchies of CPU is normally associated with hardware physical proximity CPU (just one factors) or the speed of bus that connect between CPU. Not all CPU are connected to all other CPU, but perhaps only two or 4 other CPU, and therefore, when u transfer data between CPU, it is necessary to build these proximities information into the kernel, to minimize costs of data transfer between CPU. 90% (or more) of supercomputers (with thousands of CPU) are run by Linux kernel, and clearly each CPU can only have a few neighboring CPU. Other factors involved power-management: when your processing usage goes down, u have to shut down the CPU - leaving only the bare minimum to be running. Organizing in some hierarchies facilitate this scheduling algorithm. http://www.intel.com/technology/itj/2007/v11i4/9-process/6-linux-scheduler.htm http://www.cs.stonybrook.edu/~porter/courses/cse506/f12/slides/scheduling.pdf http://www.cs.stonybrook.edu/~porter/courses/cse506/f12/slides/scheduling2.pdf -- Regards, Peter Teoh ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: why are scheduling domains used in multiprocessor systems
On 01/09/2013 01:33 PM, Bond wrote: The answer of the question that I want to know is why is a scheduling domain actually needed? Scheduling domains and scheduler groups/cpu groups help to ease the process of scheduling tasks like: 1.load balancing tasks across cpus. 2.choosing a cpu for a new task to run on. 3.choosing a cpu for a sleeping task to run when it wakes up. It has a two fold advantage: 1.It organises the cpus in the system very well into groups and hierarchies. 2.It organises the cpus in such a way that it is useful.All cpus which share an l2 cache belong to one domain.All cpus which share an l3 cache belong to a higher level domain,which encompasses all the domains which share the l2 cache. The advantages that you see with a tree like data structure are similar here to the advantages of scheduler domains and groups. Let me explain the use cases with a simple diagram: _sd1 /\ -- l3 cache -- - -- l2 cachel2 cache - -- cpu0 cpu1 cpu2 cpu3 \___/ \/ sd0 sd0 sd1_ /\ -- l3 cache -- - -- l2 cachel2 cache - -- cpu4 cpu5 cpu6 cpu7 \___/ \/ sd0 sd0 What you see above is a scheduler domain hierarchy.sd1 encompasses sd0s which happen to be scheduler groups of sd1.Every cpu has a scheduler domain hierarchy associated with it.For eg. cpu0-sd=sd0; sd0-parent=sd1.This way through a linked list we can iterate through all the scheduler domains to which a cpu belongs to. How does this help? 1.load balancing: Say cpu0 is idle and is ready to pull tasks upon itself to relieve any other burdened cpu.In the above approach,it first checks if the other cpus that belong to the first level sched domain ,needs to be relieved of load.Here, cpu1.If so it takes on tasks from cpu1,else it goes to the higher level domain sd1.If it chooses to migrate task from cpu1 it is the best thing,because the cache contents can be utilized;shared cache.no need to fetch from memory again.This is the first advantage:sched domains are formed based upon the advantages that hardware has to provide. If it goes to sd1,then it probes sd1's 'groups',both the sd0s.Here is the next advantage.It needs information about the sched group alone and will not bother about the individual cpus in it.it checks if load(sd0[cpu2,cpu3]) load(sd0[cpu0,cpu1]) Only if this is true does it go on to see if cpu2/3 is more loaded.If there were no scheduler domain or groups,we would have to see the states of cpu2 and cpu3 in two iterations instead of 1 iteration like we are doing now. Now scale this problem and solution to 128 cpus! imagine what a mess it would have been if there was nothing to tell you which cpu would be the best to relieve load from,in the worst case you would have to iterate through all the 128 cpus. But with scheduler domain or groups,say you divide the 128 cpus into groups of 16 cpus,you would have 8 groups.see which is the busiest,so that would be 8 iterations,then you would know the busiest group,then descend down.another 16 iterations.so worst case 8+16 = 24 iterations.And this decrease is only with one level of sched domain. Imagine if you had more levels,you would make the number of iterations even lower. So in short the scheduler domains and groups are a 'divide and conquer ;but conquer as much as possible what is more useful' solution to scheduling related stuff :) Thank you Regards Preeti U Murthy ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Cross Compiling a different architechture
x86 build is done but wont boot up using the build using the vmlinux image. using usb stick. any tips? TnR, Ganesh From: Ganesh B ganeshsu...@yahoo.com To: Anuz Pratap Singh Tomar chambilketha...@gmail.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 1:09 PM Subject: Re: Cross Compiling a different architechture Yes, you touch the pain area I am facing. I could build x86 as well as i386 toolchain. Though I have not tried the image yet. But when cross compiling arm and arm64 say for example, I receive .config related errors which either does not create the .config or gives errors like I mentioned. Would I be able to do a allyesconfig for this? If yes, what options needs to be missed or edited to get the processor selection at runtime. using i386 machine $make ARCH=arm defconfig - ends up with errors of hardware conpatibility of i386, .config not created $make ARCH=arm allyesconfig - ends up with errors of hardware conpatibility specially sub-architecture of processor, .config not created $make ARCH=arm menuconfig - all options enabled gives while building, .config created but kernel not built while using make TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 12:20 PM Subject: Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 12:06 PM, Ganesh B ganeshsu...@yahoo.com wrote: Okay makes sense let me try clean before building different arch. I am not doing this at the moment. Would I need to have different toolchains for same architecture, I was trying to build for all processor types for an arch using a different toolchain but it failed? You _may_ require different toolchains for different processor with same arch types, for example under x86, i386 and i586 toolchains _may_ be used interchangably but not ia64 or x86_64 or may not even for atom. Similarly in ARM, there are different families of processor and there may be big endian or small endian processor. So you may have to find the correct toolchain for the given config. Ones that passed the different cross-compile arch failed at some modules speciially the net, sound, video, or built_in sections. Let me check this and revert. Have you ever compiled a complete end to end allyesconfig for a same or cross-compile build? allyesconfig gave me dependency/ missing/ invalid entry errors for cross-compile arch like arm. Why would you do enable all config options? There may be incompatible dependencies, which will ofcourse lead to compilation errors. I generally get .config files from elsewhere, sometimes there are files inside the source somewhere or sometimes you just do make ARCH=XXX menuconfig and then configure the options selectively. I may try to build toolchain for raspberry pi in few days and see if I face such issues or not(but that is highly tentative. ) TnR, Ganesh From: Anuz Pratap Singh Tomar chambilketha...@gmail.com To: Ganesh B ganeshsu...@yahoo.com Cc: kernelnewbies@kernelnewbies.org kernelnewbies@kernelnewbies.org Sent: Wednesday, January 9, 2013 11:19 AM Subject: Re: Cross Compiling a different architechture On Wed, Jan 9, 2013 at 3:30 AM, Ganesh B ganeshsu...@yahoo.com wrote: I do not know why but whether ncurses or menuconfig the build fails at some modules (specially hardware architecture ones), specially at cross compiling architecture build stage. It went smoothly for same system architecture like i386 or x86 but not for arm or arm64. Where is the doc's for Kernel defconfig and kconfig in Kernel.org? I am trying to make and edit each manually for each architecture and then run make all. The problem is it is not allowing me to assemble all sub-architectures for say arm or arm64 as a dynamic module. I have to specify and select each option (sub-hardware architecture) specifically during build of defconfig for the architecture. My x86 is also blocking the build at times. I did not get anything good on my google search. I would say a wiser choice would be getting a .config from somewhere and editing options which you really need to change. I am not sure if you understand this or not, but you need to have a series of toolchains for each arch you need to cross compile at different locations. For different binaries of different arch, I would suggest you use different directories of same source code. Generally make clean or distclean should get rid of most binaries, but starting a clean build is always the best idea. Toolchains can be bit of a pain to get right. w.r.t. Knoppix, Thank you, let me check the informit link for the architecture and usage relevance. TnR, Ganesh
