malloc memory region descriptors

Dear All, In linux kernel, for all memory allocation done by *vmalloc*, kernel maintains memory region descriptor *(vm_struct)* which stores information about the linear virtual address range, no. of physical page frames allocated... as a linked list headed by *vmlist *symbol. Can you

Re: unconsistency of state of irq

2010/8/15 Parmenides mobile.parmeni...@gmail.com: Hi,   For each irq descriptor, there is a state bit IRQ_DISABLED indicating whether corresponding IRQ is masked. But, when checking the source code, I find that the function mask_and_ack_8259A(), which is responsible for acknowledge the PIC

Re:

On Mon, Aug 16, 2010 at 2:46 PM, Tejas Upadhyay upadhya...@gmail.comwrote:

Re: malloc memory region descriptors

On Mon, Aug 16, 2010 at 1:00 AM, Prabhu nath gprabhun...@gmail.com wrote: Dear All, *I understand that kernel maintains a descriptor (*vm_area_struct*) per application to hold information about the virtual address space allocated for the heap region.* Not entirely true. the linux

Re: malloc memory region descriptors

On Mon, Aug 16, 2010 at 1:30 PM, Prabhu nath gprabhun...@gmail.com wrote: Dear All, In linux kernel, for all memory allocation done by *vmalloc*, kernel maintains memory region descriptor *(vm_struct)* which stores information about the linear virtual address range, no. of physical

Re: malloc memory region descriptors

On Mon, 16 Aug 2010 16:40:20 +0530 Prabhu nath gprabhun...@gmail.com wrote: On Mon, Aug 16, 2010 at 1:30 PM, Prabhu nath gprabhun...@gmail.com wrote: Dear All, In linux kernel, for all memory allocation done by *vmalloc*, kernel maintains memory region descriptor

Why the size of pid hash tables depends on the size of RAM?

Hello list, In Understanding the Linux kernel book, it was said that the size of pid hash table depends on the size of RAM; for example, for the systems having 512MB of RAM, each hash table is stored in 4 page frames and includes 2,048 entries. How is the size of pid hash table determined? I

Re: malloc memory region descriptors

On Mon, Aug 16, 2010 at 15:00, Prabhu nath gprabhun...@gmail.com wrote: Dear All,   In linux kernel, for all memory allocation done by vmalloc, kernel maintains memory region descriptor (vm_struct) which stores information about the linear virtual address range, no. of physical page

Re: why is it necessary that irqs are disabled to preempt?

On 08/16/2010 03:48 AM, Parmenides wrote: if (!current_thread_info-preempt_count !irqs_disabled()) { current_thread_info-preempt_count = PREEMPT_ACTIVE; schedule(); current_thread_info-preempt_count = 0; } The if statement checks whether irqs are enabled.

Re: why is it necessary that irqs are disabled to preempt?

On Mon, Aug 16, 2010 at 14:48, Parmenides mobile.parmeni...@gmail.com wrote: The if statement checks whether irqs are enabled. If so, the preemption will be carried out. I wonder why this check is necessary. Why preemption is prohibited with irqs disabled? Because that likely means we are

Re: malloc memory region descriptors

On Mon, Aug 16, 2010 at 4:10 AM, Prabhu nath gprabhun...@gmail.com wrote: On Mon, Aug 16, 2010 at 1:30 PM, Prabhu nath gprabhun...@gmail.comwrote: Dear All, In linux kernel, for all memory allocation done by *vmalloc*, kernel maintains memory region descriptor *(vm_struct)*

Re: How create a miscellaneous crw-rw-rw- device ?

HI Stephan, So you'll  either need to modify your global umask, or add a udev rule for your driver  which explicitly sets the mode. I use to build under my nonpriv-account but I need the root to insmod/rmmod. The root account has a standard umask of 0022. This is:          umask -S

Re: why is it necessary that irqs are disabled to preempt?

On Mon, Aug 16, 2010 at 8:49 PM, Rik van Riel r...@nl.linux.org wrote: On 08/16/2010 03:48 AM, Parmenides wrote:     if (!current_thread_info-preempt_count  !irqs_disabled()) {         current_thread_info-preempt_count = PREEMPT_ACTIVE;         schedule();