Re: Kernel updating : export gpio not working ?
Hi, Thank you for your answer ! :) No problem to post back my solution. I think it can always be useful to know the solution of a problem even if it is a specific one. And I would be happy if it could help other kernel-newbies not to do the same error ;) Best regards, -- Mylène JOSSERAND Le 27/02/2013 18:42, Mulyadi Santosa a écrit : On Wed, Feb 27, 2013 at 10:19 PM, Mylene Josserand mylene.josser...@navocap.com wrote: Just to update you that I have found my problem ! In my config file, I did not notice that my own board and an other imx27 board was enabled ! So the gpios configured was the one from this board and not mine's (thanks debugfs !). That is why it did not act like I wanted. This is the kind of post that I like most some one has problem but he/she also still find a way to solve. Then post it back to kernelnewbies. Nice info to know. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
doesn't ioremap() retrun contigious addressess...?
Hi All
Please find a piece of code that i wrote in my driver,
void __iomem *tcpm_base = ioremap_nocache(0x0390, SZ_16KB);
printk(Virtual addresss %x\n,tcpm_base);
if(tcpm_base!=NULL)
{
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
for(i=0;i(SZ_16KB-1);i++)
src = readl(tcpm_base+i);
printk(%d\n,src);
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
}
else
printk(unable to map \n);
When i execute this code, i am seeing a kernel panic telling
- LOG
Virtual addresss ea88
Unable to handle kernel paging request at virtual address ea89
-LOG-
If you observe,
virtual address of tcpm_base is ea88.
if ioremap() returns all contigious memory, There should be no
dereferencing of ea89(the max address should be ea88fffe)
But in kernel logs show, it is dereferencing that address.
My question now is...
doesn't ioremap() returns contigious address space?
With regards,
Sandeep Kumar Anantapalli,
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Re: doesn't ioremap() retrun contigious addressess...?
Sorry, Neglect the question.
i am using a readl() which reads 4 bytes at a time. In the last iteration,
it is trying to read next 4 unmapped locations.
On Thu, Feb 28, 2013 at 4:06 PM, sandeep kumar coolsandyfor...@gmail.comwrote:
Hi All
Please find a piece of code that i wrote in my driver,
void __iomem *tcpm_base = ioremap_nocache(0x0390, SZ_16KB);
printk(Virtual addresss %x\n,tcpm_base);
if(tcpm_base!=NULL)
{
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
for(i=0;i(SZ_16KB-1);i++)
src = readl(tcpm_base+i);
printk(%d\n,src);
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
}
else
printk(unable to map \n);
When i execute this code, i am seeing a kernel panic telling
- LOG
Virtual addresss ea88
Unable to handle kernel paging request at virtual address ea89
-LOG-
If you observe,
virtual address of tcpm_base is ea88.
if ioremap() returns all contigious memory, There should be no
dereferencing of ea89(the max address should be ea88fffe)
But in kernel logs show, it is dereferencing that address.
My question now is...
doesn't ioremap() returns contigious address space?
With regards,
Sandeep Kumar Anantapalli,
--
With regards,
Sandeep Kumar Anantapalli,
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Re: doesn't ioremap() retrun contigious addressess...?
Yes, ioremap() maps the given physical address to contiguous Kernel virtual
address above high_memory and returns the first address of the mapped
kernel virtual address.
Regards,
Prabhu
On Thu, Feb 28, 2013 at 4:06 PM, sandeep kumar coolsandyfor...@gmail.comwrote:
Hi All
Please find a piece of code that i wrote in my driver,
void __iomem *tcpm_base = ioremap_nocache(0x0390, SZ_16KB);
printk(Virtual addresss %x\n,tcpm_base);
if(tcpm_base!=NULL)
{
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
for(i=0;i(SZ_16KB-1);i++)
src = readl(tcpm_base+i);
printk(%d\n,src);
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
}
else
printk(unable to map \n);
When i execute this code, i am seeing a kernel panic telling
- LOG
Virtual addresss ea88
Unable to handle kernel paging request at virtual address ea89
-LOG-
If you observe,
virtual address of tcpm_base is ea88.
if ioremap() returns all contigious memory, There should be no
dereferencing of ea89(the max address should be ea88fffe)
But in kernel logs show, it is dereferencing that address.
My question now is...
doesn't ioremap() returns contigious address space?
With regards,
Sandeep Kumar Anantapalli,
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Re: doesn't ioremap() retrun contigious addressess...?
I guess your reading is wrong. If you are mapping 16KB of physical address
from 0x0390. The mapping is as follows.
0x0390 to 0x03903FFF -- 0xEA88 to 0xEA883FFF
For every iteration you are reading 4 bytes. hence you have to reduce your
loop as follows and also declare tcpm_base as unsigned int *
unsigned int __iomem *tcpm_base;
*tcpm_base = ioremap_nocache(0x0390, SZ_16KB);
printk(Virtual addresss %x\n,tcpm_base);
if(tcpm_base!=NULL)
{
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
for(i=0;i*0xFFF*;i++)
src = readl(tcpm_base+i);
printk(%d\n,src);
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
}
else
printk(unable to map \n);
Regards,
Prabhu
On Thu, Feb 28, 2013 at 4:41 PM, Prabhu nath gprabhun...@gmail.com wrote:
Yes, ioremap() maps the given physical address to contiguous Kernel
virtual address above high_memory and returns the first address of the
mapped kernel virtual address.
Regards,
Prabhu
On Thu, Feb 28, 2013 at 4:06 PM, sandeep kumar
coolsandyfor...@gmail.comwrote:
Hi All
Please find a piece of code that i wrote in my driver,
void __iomem *tcpm_base = ioremap_nocache(0x0390, SZ_16KB);
printk(Virtual addresss %x\n,tcpm_base);
if(tcpm_base!=NULL)
{
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
for(i=0;i(SZ_16KB-1);i++)
src = readl(tcpm_base+i);
printk(%d\n,src);
printk(Jiffies %x %ld\n\n\n\n, jiffies, jiffies);
}
else
printk(unable to map \n);
When i execute this code, i am seeing a kernel panic telling
- LOG
Virtual addresss ea88
Unable to handle kernel paging request at virtual address ea89
-LOG-
If you observe,
virtual address of tcpm_base is ea88.
if ioremap() returns all contigious memory, There should be no
dereferencing of ea89(the max address should be ea88fffe)
But in kernel logs show, it is dereferencing that address.
My question now is...
doesn't ioremap() returns contigious address space?
With regards,
Sandeep Kumar Anantapalli,
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Re: doesn't ioremap() retrun contigious addressess...?
Le jeudi 28 février 2013 à 16:25 +0530, sandeep kumar a écrit : Sorry, Neglect the question. i am using a readl() which reads 4 bytes at a time. In the last iteration, it is trying to read next 4 unmapped locations. So you probably have to do this instead: for(i=0;i(SZ_16KB-1)/4;i++) src = readl(tcpm_base+(i * 4)); Regards -- Yann Droneaud OPTEYA ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: doesn't ioremap() retrun contigious addressess...?
Yep. On Thu, Feb 28, 2013 at 5:10 PM, Yann Droneaud ydrone...@opteya.com wrote: Le jeudi 28 février 2013 à 16:25 +0530, sandeep kumar a écrit : Sorry, Neglect the question. i am using a readl() which reads 4 bytes at a time. In the last iteration, it is trying to read next 4 unmapped locations. So you probably have to do this instead: for(i=0;i(SZ_16KB-1)/4;i++) src = readl(tcpm_base+(i * 4)); Regards -- Yann Droneaud OPTEYA ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: doesn't ioremap() retrun contigious addressess...?
Thank you all, It worked :) On Thu, Feb 28, 2013 at 5:33 PM, Prabhu nath gprabhun...@gmail.com wrote: Yep. On Thu, Feb 28, 2013 at 5:10 PM, Yann Droneaud ydrone...@opteya.comwrote: Le jeudi 28 février 2013 à 16:25 +0530, sandeep kumar a écrit : Sorry, Neglect the question. i am using a readl() which reads 4 bytes at a time. In the last iteration, it is trying to read next 4 unmapped locations. So you probably have to do this instead: for(i=0;i(SZ_16KB-1)/4;i++) src = readl(tcpm_base+(i * 4)); Regards -- Yann Droneaud OPTEYA ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- With regards, Sandeep Kumar Anantapalli, ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
64bit MMIO access
Hi, What are the read/write kernel functions to access 64bit MMIO addresses? Are there similar functions like readl() and writel() for 64bit systems? Regards, Jagath ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
64bit MMIO access
Hi, What are the read/write kernel functions to access 64bit MMIO addresses? Are there similar functions like readl() and writel() for 64bit systems? Regards, Jagath ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: How to measure the RAM read/write performance
On Tue, Feb 26, 2013 at 6:50 PM, ankur dwivedi ankurengg2...@gmail.com wrote:
I am not sure but what if you make the variable as a volatile?
Volatile in simple terms
==
Consider this eg:
1 int main(void){
2 int a, x, y;
3 x=a;
4 y=a;
5 }
Line 3 with be converted to a LDR instruction.
Line 4 is where the compiler optimization comes in. It may be loaded
from the previous loaded register.
Line 3: ldr r0[r1]; r1 is having the address of a
Line 4: mov r2 r0; because we have value of a already in r0.
But if a is volatile variable, then compiler places ldr for both
instructions(ie for x=a and y = a).
so line 4 will change as follows.
Line 3: ldr r0[r1];r1 is having the address of a
Line 4: ldr r2[r1]; r1 is having the address of a
But if cache is enabled, ldr can fetch the data from cache if present.
So volatile cannot help us here.
Thanks,
Arun
On Tue, Feb 26, 2013 at 5:01 PM, sandeep kumar coolsandyfor...@gmail.com
wrote:
Hi All
In performance benchmark tools, When we profile read/write timings mostly,
those read/writes are done to cache only.
I want to measure my DDR(RAM chip) performance.
So i want to make sure, every read/write should happen to DDR RAM chip
only.
How can i achieve this...Any ideas/suggestions...?
--
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Sandeep Kumar Anantapalli,
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--
Thanks
Ankur Dwivedi
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Re: relocatable modules' symbols
Hi Horseriver,
On Sun, Feb 24, 2013 at 7:26 AM, horseriver horseriv...@gmail.com wrote:
On Sun, Feb 24, 2013 at 04:00:37PM +0700, Mulyadi Santosa wrote:
On Sat, Feb 23, 2013 at 6:45 AM, horseriver horseriv...@gmail.com wrote:
hi:
I have built vmlinux at the top dir of kernel source ,then I use objdump
to look into
its section information.I find the statup_32 which is the start routine
of kernel ,
locats at 0xc010. I know the 0x10 is the defined address for
locating
protect-mode code .But which I can not understand is the 0xc prefix
.where does it come from?
If my guess is right, that's because kernel mode code start at
0xc00 a.k.a a bit above 3 GiB on x86 32 bit machine
I have find this answer .
It is defined in lds script file .
here is the code :
SECTIONS
{
. = 0xC000 + 0x10;
/* read-only */
_text = .;/* Text and read-only data */
why use 0xC000 as its start ? why not just use 0x10 only ?
if use 0xC000,every linked symbole will be prefixed by 0xc , what is
the purpose ?
Usually, user kernel space split is 3G:1G.
ie 1G for kernel space. And this starts from 0xC000_ till 0x_
All the address below 0xC000_(ie 3G from 0x0 to 0xBFFF_) is
used for user space.
Thanks,
Arun
thanks!
--
regards,
Mulyadi Santosa
Freelance Linux trainer and consultant
blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com
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Re: atomic operations
Hi Peter, On Sun, Feb 24, 2013 at 6:20 PM, Peter Teoh htmldevelo...@gmail.com wrote: in simple terms, any operation, in terms assembly instructions, which can be executed in ONE instruction, is atomic, because, just like an atom, it cannot be broken up into parts. any instructions that is longer than one, for eg, TWO instruction, is NOT atomic, because in BETWEEN the first and 2nd instruction, something like an interrupt can come in, and affect the values of the operand when it is passed from instruction one to second instruction. Nice explanation. Thanks, Arun To save me from reiteration: http://www.ibm.com/developerworks/library/pa-dalign/ (search for atomicity). http://stackoverflow.com/questions/381244/purpose-of-memory-alignment http://lwn.net/Articles/260832/ http://www.songho.ca/misc/alignment/dataalign.html http://www.cis.upenn.edu/~palsetia/cit595s08/Lectures08/alignmentOrdering.pdf Essentially, atomicity and non-alignment become problematic when u tried to to read using non-byte addressing mode with non-aligned address. On Sun, Feb 24, 2013 at 5:42 PM, Shraddha Kamat sh200...@gmail.com wrote: what is the relation between atomic operations and memory alignment ? I read from UTLK that an unaligned memory access is not atomic please explain me , I am not able to get the relationship between memory alignment and atomicity of the operation. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies -- Regards, Peter Teoh ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: Examples of Per-CPU Variables in Kernel source
On Sun, Feb 24, 2013 at 2:07 PM, Shraddha Kamat sh200...@gmail.com wrote: I was reading about Per-CPU Variables from UTLK. Where are such variables used in the kernel source code - example. Use grep utility to find it out . Thanks, Arun -- Shraddha ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
