January 2013 - kernelnewbies@kernelnewbies.org

what does this error mean?
by John Smith Jan. 16, 2013

Jan. 16, 2013

/usr/bin/ld: arch/i386/kernel/vsyscall-int80.so: Not enough room for program headers, try linking with -N

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Does driver wake_up a wait_queue on a socket file?
by horseriver Jan. 15, 2013

Jan. 15, 2013

hi: When an net IRQ on a socket reached, does the driver wake_up socket's wait_queue at once ? thanks!

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How to boot linux kernel with boches ?
by horseriver Jan. 15, 2013

Jan. 15, 2013

hi: I have compiled kernel 2.6 , and want to boot with boches to debug some modules . How can I boot it up first ? How to edit the bochsrc.txt configure file? thanks!

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struct nbd_reply not packed => trouble?
by Sebastian Pipping Jan. 15, 2013

Jan. 15, 2013

Hello kernel hackers, I noticed that in [linux]/include/uapi/linux/nbd.h the structure struct nbd_request { __be32 magic; __be32 type; /* == READ || == WRITE */ char handle[8]; __be64 from; __be32 len; } __attribute__((packed)); is packed but its reply counter part struct nbd_reply { __be32 magic; __be32 error; /* 0 = ok, else error */ char handle[8]; /* handle you got from request */ }; is not. Since Linux seems to read sizeof(nbd_reply) bytes from the network (see [1]), the number of bytes read varies with the number of bytes of the structure. So my understanding is that if the size of struct nbd_reply varies from platform/compiler to another that means trouble. I wonder: - Is there anything about struct nbd_reply that would keep its size equal everywhere or a reason why variance in size is no problem here? - Any ideas for a platform where you would expect struct nbd_reply to be other than 4 + 4 + 8 = 16 bytes in size? Best, Sebastian [1] http://lxr.linux.no/#linux+v3.7.1/drivers/block/nbd.c#L336

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what is the difference between poll and epoll ?
by horseriver Jan. 15, 2013

Jan. 15, 2013

hi: I know epoll is event triger model ,but I do not know internel surpport for it . is there some illustration for epoll's frame or internel implementation? thanks!

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Re:Kernelnewbies Digest, Vol 26, Issue 38
by ★随风行∮ Jan. 15, 2013

Jan. 15, 2013

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Re: what does this do ?
by Anuz Pratap Singh Tomar Jan. 14, 2013

Jan. 14, 2013

On Mon, Jan 14, 2013 at 6:02 AM, horseriver <horserivers(a)gmail.com> wrote: > On Mon, Jan 14, 2013 at 02:44:11PM +0000, Anuz Pratap Singh Tomar wrote: > > On Mon, Jan 14, 2013 at 4:50 AM, horseriver <horserivers(a)gmail.com> > wrote: > > > > > On Sun, Jan 13, 2013 at 09:27:45PM -0800, Dave Hylands wrote: > > > > Hi, > > > > > > > > On Sun, Jan 13, 2013 at 11:29 AM, horseriver <horserivers(a)gmail.com> > > > wrote: > > > > > > > > > > hi: > > > > > > > > > > In kernel code . some function is defined by > > > > __attribute__((__section__(".initcall" level ".init"))) > > > > > > > > > > what does this do ? > > > > > > > > It puts the address of the function in a linker section named > > > > .initcallX.init where X is replaced by the level. > > > > > > > > These functions are called in order to initialize various subsystems > and > > > > drivers during kernel bootup. > > > > > > Thanks! > > > > > > Another question: > > > > > > __attribute__((regparm(3))) ; what does this do ? > > > > > > > > > > > > A simple google search should have answered this > > http://ohse.de/uwe/articles/gcc-attributes.html > > > > Synopsis > > > > regparm (NUMBER) Found in versions: 2.7-3.4 Description: > > > > Functions that take a variable number of > > arguments will continue to be passed all of their arguments on the > > stack. > > > > what does this mean? > > > May be you should really read more. I would suggest reading some i386 assembly. Thank you Warm Regards Anuz

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Re: build rules for subdirs in kernel source
by horseriver Jan. 14, 2013

Jan. 14, 2013

On Mon, Jan 14, 2013 at 10:44:28PM +0530, Vivek Gautam wrote: > Hi, > > > On Mon, Jan 14, 2013 at 10:36 AM, horseriver <horserivers(a)gmail.com> wrote: > > hi: > > > > How to build targets for every subdirs of kernel ? > > > > Is it the Makefile you want to look for. > Make is the same linux utility to build a project consisting of multiple files. > > > for example : drivers/* > > > So we club the directories / subdirectories or files in the Makefile > in order to compile (build them) > Something like this: > > http://lxr.free-electrons.com/source/drivers/Makefile > > > I do not find the rules for build subdir's target > > > > Individual sub directories or files may be built based on some kernel > config defined in Kconfig > > > > > thanks! > > Hope this explains some of your doubts. Yeah!:) What is the use of scripts/makefile.build ? Thanks! > > -- > Thanks & Regards > Vivek

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Re: where is the build rule for kernel's subdirs?
by horseriver Jan. 14, 2013

Jan. 14, 2013

On Mon, Jan 14, 2013 at 08:32:57AM -0800, Randy Dunlap wrote: > On 01/13/13 20:33, horseriver wrote: > > hi: > > > > How does kbuild build objects for subdirs of kernel source ? > > It goes into subdirs recursively. > > > From top-level Makefile: > > # Objects we will link into vmlinux / subdirs we need to visit > init-y := init/ > drivers-y := drivers/ sound/ firmware/ > net-y := net/ > libs-y := lib/ > core-y := usr/ > > > Then each subdir's Makefile has its own rules. I do not think so ! every makefile in these subdirs only have defined obj files ,but not contained build rules . Thanks! > > -- > ~Randy

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what does this do ?
by horseriver Jan. 14, 2013

Jan. 14, 2013

hi: In kernel code . some function is defined by __attribute__((__section__(".initcall" level ".init"))) what does this do ? thanks!

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