Re: On loading userspace data into particular section of physical memory (ARM)
Hi Joel... On Wed, Dec 5, 2012 at 12:07 PM, Joel A Fernandes agnel.j...@gmail.com wrote: I am looking at a problem that might be too difficult to solve, or might not if I'm missing something so I thought I'd bounce it off this group, Basically I have an application in userspace who's .data section _has_ to be loaded into particular locations in physical memory. That is, there is a chunk of physical memory that has to contain the .data section and no other part of physical memory should. What is the easiest way to do this? I guess, changes might be required to the ELF loaders in fs/bin*.c. Any other tricks? I somewhat agree that the solution would be changing some parts in ELF loader. But not sure which one, loader in kernel space, user space or both. PS: are you considering creating special data section? perhaps by using custom ld script? -- 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
Re: On loading userspace data into particular section of physical memory (ARM)
Hi Mulyadi, How are you doing? PS: are you considering creating special data section? perhaps by using custom ld script? Yes, that would be a possiblity. Regards, Joel ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
On loading userspace data into particular section of physical memory (ARM)
I am looking at a problem that might be too difficult to solve, or might not if I'm missing something so I thought I'd bounce it off this group, Basically I have an application in userspace who's .data section _has_ to be loaded into particular locations in physical memory. That is, there is a chunk of physical memory that has to contain the .data section and no other part of physical memory should. What is the easiest way to do this? I guess, changes might be required to the ELF loaders in fs/bin*.c. Any other tricks? Is it non-trivial to add a new memory zone to the kernel that manages a particular section of physical memory? I thought if a new zone could be added, then we could possibly modify the kernel ELF loader to recognize a specially marked .data section and alloc memory from that special zone when allocating page frames. Let me know if you have any ideas, Thanks, Regards, Joel ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
Re: On loading userspace data into particular section of physical memory (ARM)
Hi, On Tue, Dec 4, 2012 at 11:07 PM, Joel A Fernandes agnel.j...@gmail.comwrote: I am looking at a problem that might be too difficult to solve, or might not if I'm missing something so I thought I'd bounce it off this group, Basically I have an application in userspace who's .data section _has_ to be loaded into particular locations in physical memory. That is, there is a chunk of physical memory that has to contain the .data section and no other part of physical memory should. This is something unconventional. I wouldn't expect user space to mandate that. I think you are approaching the problem in a wrong way. What is the easiest way to do this? I guess, changes might be required to the ELF loaders in fs/bin*.c. Any other tricks? Why would you want to do that? Even if you do that, how are you going to achieve this for just your application. What even you change here (even if that the right place to do it), would be applicable for all processes. I dont think you want that, do you? Is it non-trivial to add a new memory zone to the kernel that manages a particular section of physical memory? I thought if a new zone could be added, then we could possibly modify the kernel ELF loader to recognize a specially marked .data section and alloc memory from that special zone when allocating page frames. Let me know if you have any ideas, Thanks, I am not sure why you would need data section to be in a certain physical memory, but if all you want is to copy a certain data from userspace to be shared with a peripheral or some thing that could be done. One way to do it would be to have a driver (you own memory manager if you will) that would reserve this physical memory during bootup, and then can have a char device interface that you would call from your user app to request for memory. Would be interesting to see your use case! Regards, Joel ___ 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: On loading userspace data into particular section of physical memory (ARM)
On Tue, Dec 4, 2012 at 11:19 PM, Subramaniam Appadodharana c.a.subraman...@gmail.com wrote: Hi, On Tue, Dec 4, 2012 at 11:07 PM, Joel A Fernandes agnel.j...@gmail.com wrote: I am looking at a problem that might be too difficult to solve, or might not if I'm missing something so I thought I'd bounce it off this group, Basically I have an application in userspace who's .data section _has_ to be loaded into particular locations in physical memory. That is, there is a chunk of physical memory that has to contain the .data section and no other part of physical memory should. This is something unconventional. I wouldn't expect user space to mandate that. I think you are approaching the problem in a wrong way. It is unconventional of course. What is the easiest way to do this? I guess, changes might be required to the ELF loaders in fs/bin*.c. Any other tricks? Why would you want to do that? Even if you do that, how are you going to achieve this for just your application. What even you change here (even if that the right place to do it), would be applicable for all processes. I dont think you want that, do you? No, just for this process if we could use any directives that could mark the section in a certain way. Is it non-trivial to add a new memory zone to the kernel that manages a particular section of physical memory? I thought if a new zone could be added, then we could possibly modify the kernel ELF loader to recognize a specially marked .data section and alloc memory from that special zone when allocating page frames. Let me know if you have any ideas, Thanks, I am not sure why you would need data section to be in a certain physical memory, but if all you want is to copy a certain data from userspace to be shared with a peripheral or some thing that could be done. One way to do it would be to have a driver (you own memory manager if you will) that would reserve this physical memory during bootup, and then can have a char device interface that you would call from your user app to request for memory. No, that would require modifications to the userspace code itself which doesn't work as there is lots of code that needs to be changed. What would be an ideal solution is if the whole physical memory allocation transparent to the user process involved. Would be interesting to see your use case! The use case is one of- separating the code and data section into different physical memory areas. Currently, kernel allocates pages for user code and data mixed interspersed across physical memory (without caring about whether its code or data). This works fine, but incurs a very high performance hit for a certain application. ___ Kernelnewbies mailing list Kernelnewbies@kernelnewbies.org http://lists.kernelnewbies.org/mailman/listinfo/kernelnewbies
