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finding kernel jump address after "decompressing linux"
by Christopher Harvey June 30, 2011

June 30, 2011

I'm trying to figure out what physical address the kernel jumps to after "Uncompressing Linux... done, booting the kernel.". IIRC, there are two parts to a kernel image, one compressed part and one uncompressed. The uncompressed code decompresses the compressed part and puts it into memory then jumps to it. I'm using an ARM kernel, version 2.6.38. thanks, Chris

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Kernel log mechanism: How to log messages in a different file
by amit mehta June 30, 2011

June 30, 2011

Hi, I've written some kernel modules using kprobes infrastructure to grab some more information on network packets. I've lots of printk which by default show up in syslog file(/var/log/messages), I was wondering if there are some method to redirect my printkS to appear in somewhere else(say /var/log/netlog). On a busy system, it gets little cluttered with other logs. Of-course i can grep for my own custom messages but it would be lot more convenient if i can redirect my messages in a separate log file. Considering above can be done, then what about dmesg ? will they still show up in dmesg output ? Regards, Amit

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Gmail complaining about authenticity of emails sent/received via kernelnewbies
by Mandeep Sandhu June 30, 2011

June 30, 2011

Hi All, I'm using gmail.com for corresponding to this mailing list. Recently I have observed that gmail has started complaining about the authenticity of the sender. Eg: I see this message quite often when someone replies to a kernewbies post: This message may not have been sent by: xyz(a)gmail.com Is anyone else seeing this too? I think mailing lists set a "via" (or some such) header in the mail to indicate that the mail is being sent on behalf of the original sender. Could that be missing? -mandeep

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what is "can't copy type 0"?
by Joy Sun June 30, 2011

June 30, 2011

Hi, While compiling kernel, I'm seeing this warning message: can't copy type 0 but, it looks no issue has found while running the kernel image in my system. However, just from my curiosity. What is the warning message? And, what problem is related? If you know, would you share of it, please? Thanks, - Joy

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link question
by Littlefield, Tyler June 29, 2011

June 29, 2011

I have a quick question; this is something I haven't been able to figure out. By using the kernel headers you can call functions that are defined in the kernel, but you don't actually have to link to the kernel or any sort of library. How does this work? How does compiled code call the function if it doesn't link to it in some way or another?. -- Take care, Ty my website: http://tds-solutions.net my blog: http://tds-solutions.net/blog skype: st8amnd127 My programs don't have bugs; they're randomly added features!

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Re: Problem in compiling kernel
by Daniel Baluta June 29, 2011

June 29, 2011

On Tue, Jun 28, 2011 at 2:07 PM, Ponkumaran Annadurai <aspkumaran(a)gmail.com> wrote: > > > On Tue, Jun 28, 2011 at 1:13 PM, Daniel Baluta <daniel.baluta(a)gmail.com> > wrote: >> >> >> Have you tried to setup some sort of cross-compilation environment? >> >> Could you check CROSS_COMPILE env variable? >> >> > Yes, I have given yes for that option during configuration >> >> OK, then that's your problem. CROSS_COMPILE is a string >> pointing to your cross compiler prefix. >> >> thanks, >> Daniel. > > > Yes, It worked. Thank you sir. But I couldn't understand the reason. Can you > explain this to me? Please keep kernelnewbies to CC:, so that other can read about this problem if they hit it. The reason for which it didn't work is that you haven't set a valid cross-compiler prefix in CROSS_COMPILE When you set a cross-compiler prefix, the value stored in CROSS_COMPILE is concatenated with the name of each tool used to compile your kernel. For example, objdump will be used as ${CROSS_COMPILE}objdump. You set CROSS_COMPILE=Y, and the tool to be used is now named Yobjdump, which obviously doesn't exist. Valid values for CROSS_COMPILE look like this: CROSS_COMPILE= mips64-octeon-linux-gnu-. Hope that things are now more clear. thanks, Daniel

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Re: Gmail complaining about authenticity of emails sent/received via kernelnewbies
by Mandeep Sandhu June 29, 2011

June 29, 2011

> It's not only this list. There are other lists which are reporting > the same message. Some lists already seem to be handling this correctly. eg: I'm subscribed to the DBUS mailing lists...so mails sent there come like this: XYZ via lists.freedesktop.org to dbus -mandeep > > Sunny >

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Re: Basic HighMeM Question
by Prabhu nath June 29, 2011

June 29, 2011

On Mon, Jun 27, 2011 at 3:58 PM, Paraneetharan Chandrasekaran < paraneetharanc(a)gmail.com> wrote: > > > On 27 June 2011 14:58, Prabhu nath <gprabhunath(a)gmail.com> wrote: > >> Please see inline. >> >> On Mon, Jun 27, 2011 at 2:42 PM, piyush moghe <pmkernel(a)gmail.com> wrote: >> >>> I have very basic some question's related to HighMem Memory Mapping: >>> >>> 1) Why can't we directly map memory in highmemory? >>> >> This question is incorrect ? Typically on a intel architecture, >> the physical address space is divided into LOWMEM and HIGHMEM region. Lower >> 896 MB is marked as LOWMEM region and >896MB as HIGHMEM. More likely in the >> intel architecture the memory is always decoded from 0x00000000. For Eg. If >> you have memory of 1GB, then 896MB is decoded to LOWMEM and the rest is >> decoded in HIGHMEM. >> >>> >>> 2) As documents at many places why is the limit of 896MB for ZONE_NORMAL? >>> >> Since this 896 MB of physical address space is directly mapped to >> the Kernel linear virtual address space i.e from (0xC0000000 to 0xF8000000). >> Also, there is a Fixed constant offset relation between VA to PA i.e. VA = >> PA + 0xC000000. This has been done to avoid any page table walk for >> translating kernel virtual address to physical address. >> Thus when kernel virtual address is generated for execution, PA is >> calculated by MMU directly, thus making kernel code execution faster. >> > > Does this mean MMU doesnt look into TLB or pagetable when the kernel > virtual address is referenced? how does the MMU know the range of direct > mapping ( i.e offset-ed mapping)? > Ideally yes, MMU should hold the range information. I do not know about Intel architecture but I have learnt that in PowerPC architecture there is a BAT register which will hold the offset information. Any comments ? > >> All the above explaination strictly holds good for Intel architecture on >> Desktop machines. >> >> Regards, >> Prabhunath >> >>> >>> >>> Regards, >>> Piyush >>> >>> _______________________________________________ >>> Kernelnewbies mailing list >>> Kernelnewbies(a)kernelnewbies.org >>> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >>> >>> >> >> _______________________________________________ >> Kernelnewbies mailing list >> Kernelnewbies(a)kernelnewbies.org >> http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies >> >> > > > -- > Regards, > Paraneetharan C >

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writting NIC driver for IPV6
by Gang Lei (雷刚) June 29, 2011

June 29, 2011

HI all: Thanks for your help in advance. Could anyone tell me how to revise NIC driver to support IPV6? Or it doesn’t need driver’s change to support IPV6? Can anyone throw some light on this question? Regards Rick

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debugging enabled? (was Re: KGDB command line options not working for kernel 2.6.32)
by Mulyadi Santosa June 28, 2011

June 28, 2011

>I have one question in this context. Should we disable optimization when >building the kernel when we wish to enable kgdb or should we leave it intact. Whenever possible, yes...disable optimization.... -O option and -g in gcc don't play nicely together according to my experience. The DWARF info will be somewhat fuzzed or even "corrupted"....so it might point to wrong source line etc -- regards, Mulyadi Santosa Freelance Linux trainer and consultant blog: the-hydra.blogspot.com training: mulyaditraining.blogspot.com

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