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Purpose of using __be16 inside a data structure?
by 陳國成 Oct. 25, 2011

Oct. 25, 2011

Hi all, Please tell me the difference between using unsigned short and __be16 to declear a variable in a data structure. For example, in include/net/inet_sock.h, struct inet_sock is decleared as struct inet_sock { __be16 inet_dport; }; not struct inet_sock { unsigned short inet_dport; }; I think it has something to do with endianness. But I see that both __le16 and __be16 are unsigned short when using gcc with -E option for little-endian and big-endian platform. Can someone give me more information? * little-endian typedef unsigned short __u16; typedef __u16 __le16; typedef __u16 __be16; * big-endian typedef unsigned short __u16; typedef __u16 __le16; typedef __u16 __be16; Regards, GC

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Re: Linux 0.02 version download
by Javier Martinez Canillas Oct. 25, 2011

Oct. 25, 2011

On Tue, Oct 25, 2011 at 9:36 AM, bob <ilikepie420(a)live.com> wrote: > He's probably doing os dev and wants something simple to learn. Stick with > 0.01 as 0.02 source is lost. Sad face. Yes I know, but I recommend either use a newer kernel or use an operating system that was written for teaching like: http://pdos.csail.mit.edu/6.828/2011/xv6.html I don't want to imagine how hard could be compiling a 0.01 kernel with GCC 4.5 and find a rootfs that is suitable for it. Best regards, -- Javier Martínez Canillas (+34) 682 39 81 69 Barcelona, Spain

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Linux 0.02 version download
by Venkateswarlu P Oct. 25, 2011

Oct. 25, 2011

I want to download Linux 0.02 version I anybody knows plese send the link I already tried in the google -- ** P VENKATESWARLU M.Tech (CSE) II year NIT Calicut ,Kerala* ** *+91-9995115752

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Is there a tool which can generate a small and simple source tree after config?
by jiangtao.jit Oct. 25, 2011

Oct. 25, 2011

Hi: While reading the kernel code 1. the huge amount of files make me scared there are too many alike functions in different files sometimes I can't figure out which one was really compiled 2. too many macros in the definition of a struct or functions declaration confused me a lot I tried to follow the generated file autoconf.h to guess the final face but it's really a difficult thing Is there a tool which can generate a small and simple source tree after config? not pre-processor just generate a small source tree contains the files and dirs which really will be compiled and no macros like CONFIG_SMP etc. according to the configuration or some other way to understand the architecture of the final working source tree? Thanks. -- 2011-10-23 jiangtao.jit

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Please help me about the default rootfs
by Renjun Qu Oct. 25, 2011

Oct. 25, 2011

Hello everyone: I am building a small embedded linux system right now. I confused that why the default rootfs must has a "dev/console" node. I have made a experiment as follow: 1st, configure the kernel(2.6.32) to support the initramfs and initrd, and set the source of the initramfs to a directory which only has a "root" node. 2nd, configure the kernel to support the root file system on nfs, and rebuild the kernel. I have created all necessary files and directories in the directory exported by the nfs server. 3rd, set the appropriate boot parameter, and boot my kernel. The result is, the kernel can successfully mount the root file system, but the "/sbin/init" program can not print any information to me. My "sbin/init" program is just a hello world program which only print some greeting information.There is a "dev/console" device node in the nfs exported directory. But if i set the source of the initramfs to empty, and redo my experiment from the 2nd step,everything will be ok. So, i think there must be a “dev/console” node in the rootfs. The real root file system already has a "dev/console" node, why default rootfs must have a dev/console node. Please help me. Best regards, Ren jun Qu

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How to interpret cat /proc/meminfo
by sandeep kumar Oct. 25, 2011

Oct. 25, 2011

Hi all, Here in my device cat /proc/meminfo is showing the following result, MemTotal: 767960 kB MemFree: 104252 kB Buffers: 14696 kB Cached: 183676 kB SwapCached: 0 kB Active: 304596 kB Inactive: 282020 kB Active(anon): 250560 kB Inactive(anon): 139488 kB Active(file): 54036 kB Inactive(file): 142532 kB Unevictable: 988 kB Mlocked: 0 kB HighTotal: 536576 kB HighFree: 23408 kB LowTotal: 231384 kB LowFree: 80844 kB SwapTotal: 0 kB SwapFree: 0 kB Dirty: 0 kB Writeback: 0 kB AnonPages: 389252 kB Mapped: 94368 kB Shmem: 816 kB Slab: 17932 kB SReclaimable: 7388 kB SUnreclaim: 10544 kB KernelStack: 5912 kB PageTables: 20064 kB NFS_Unstable: 0 kB Bounce: 0 kB WritebackTmp: 0 kB CommitLimit: 383980 kB Committed_AS: 3685728 kB VmallocTotal: 434176 kB VmallocUsed: 261584 kB VmallocChunk: 115324 kB && My kernel virtual memory lay out is like this, <5>[ 0.000000] vector : 0xffff0000 - 0xffff1000 ( 4 kB) <5>[ 0.000000] fixmap : 0xfff00000 - 0xfffe0000 ( 896 kB) <5>[ 0.000000] DMA : 0xff000000 - 0xffe00000 ( 14 MB) <5>[ 0.000000] vmalloc : 0xdf800000 - 0xfa000000 ( 424 MB) <5>[ 0.000000] lowmem : 0xc0000000 - 0xdf000000 ( 496 MB) <5>[ 0.000000] pkmap : 0xbfe00000 - 0xc0000000 ( 2 MB) <5>[ 0.000000] modules : 0xbf000000 - 0xbfe00000 ( 14 MB) <5>[ 0.000000] .init : 0xc0008000 - 0xc0049000 ( 260 kB) <5>[ 0.000000] .text : 0xc0100000 - 0xc0a26000 (9368 kB) <5>[ 0.000000] .data : 0xc0b00000 - 0xc0c464c0 (1306 kB) && In the kernel command line i had put the "vmalloc=432MB" , to reserve the vmalloc area. My question is, While in the kernel memory layout, lowmem is shown as 496MB, in /proc/meminfo LowMEMtotal is only 231MB. Why is the difference between the two? How to increase the Lowmem size with reserving my vmalloc region memory(432MB) -- With regards, Sandeep Kumar Anantapalli,

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some question about request queue in blok device
by loody Oct. 24, 2011

Oct. 24, 2011

Dear all: I found there is a member of request_queue, bounce_pfn and it will be set up by calling blk_queue_bounce_limit. it seems someone will use that when calling blk_queue_bounce, but what and when it will be called? -- Appreciate your help,

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How to avoid volatiles
by Prabhakar Lad Oct. 24, 2011

Oct. 24, 2011

Hi everyone, I had question in want eradicate volatile from here: for example: #define 0x01c40800 if ((volatile void *)pllbase == (volatile void *)DAVINCI_PLL_CNTRL0_BASE) /**HERE**/ return 8; else return pll_div(pllbase, PLLC_PREDIV); Thanks. Regards --Prabhakar

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I am hoping to develop the linux kernel, which version should I modify
by Jimmy Pan Oct. 24, 2011

Oct. 24, 2011

There is a 3.0 in my hard disk, which I downloaded around Aug 10. There is 3.0.4 and 3.1-rc4 code. Which version should I use. Since I am a newbie, I think I don't need to use the newest version. Can I use my 3.0 version, or should I download a new one? Maybe I can read the kernel source on the web, is there a way to use the source on web to make patches? Thanks in advance.

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Re: mmap local APIC address
by Vaibhav Jain Oct. 21, 2011

Oct. 21, 2011

On Wed, Oct 19, 2011 at 10:57 AM, bob <ilikepie420(a)live.com> wrote: > It would be nice to share your solution in case someone else comes into the > same problem. > Hi, It was stupid mistake. I forgot to initialize the file descriptor which was passed to mmap and therefore it was throwing "Bad file descriptor" error.i realized it after looking the errors in "man mmap". Thanks Vaibhav Jain

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