Where is MMU enabled?

Hi List, I am curious to know where is the MMU turned on in a Linux PPC system - is it the u-boot or the linux kernel? Since enabling of MMU shall be the point from where the CPU will have to generate virtual addresses - I think it should be somewhere in the kernel. The reason is that all the addr

2 PCI addresses for the PCI-PCI bridges?

Hi, AFAIK the PCI-PCI bridges are visible on two PCI buses (primary bus and secondary bus). Hence there ought to be two PCI addresses for the device - A.x.y and B.x.y, where A and B are primary and secondary bus numbers. Is this right? Thanks, Rick -- To unsubscribe from this list: send an emai

IRQF_TRIGGER_* flags

Hi, This is regarding the IRQF_TRIGGER_* macros (that can be passed in flags in request_irq()) I came acrosss while browsing the code: /* * These correspond to the IORESOURCE_IRQ_* defines in * linux/ioport.h to select the interrupt line behaviour. When * requesting an interrupt without speci

What stops the vanialla kernel from being called an RTOS?

Hi list, I have asked this before, but some of my doubts remain. So I want to know that when it comes down to code, what stops the plain linux kernel from being called RTOS? Please note that I understand that there are different Linux based patches / projects that make LInux realtime, but I want t

32 bit processors / 64 bit processors

Hi, Firstly, I'm trying to understand what exactly characterizes a procesor or an operating system as 32bit / 64 bit. I've read that it means the "native word size" of a machine. But what exactly is that? Register size? Address bus size? Anything else? Secondly, I'm trying to understand what exac

request_mem_region

Hi, I'm trying to write a simple driver using some registers of my hardware. Is a call to request_mem_region() advisory ("recommended") or compulsory before I ioremap the memory? In other words, if I don't use request_mem_region() before I start using the memory; is my driver BOUND to fail, or i

Changing Kernel 3g / 1g memory split

Hi, 1) As far as I understand the 3G / 1G split of the kernel is in virtual address space, and the Highmem / lowmem concept is in physical address space. So I just want to know that if I change the memory split (from 3g/1g to 2g/2g), then will my ZONE_NORMAL also be expanded to be (896M + 1G)? 2)

C question

Hello list, As far as I recall from K&R, isn't pointer arithmetic on a void pointer banned? And any effort to do that results in an error - because the compiler won't know by how much size to increment the pointer for a statement like "ptr++"? But then how about this: [r...@linux rick]$ cat t.c #

MIssed interrupts

Hi, If a particual IRQ line has been disabled (disable_irq()), what happens if the device on that IRQ line generates interrupt? Does it result in missed interrupt? And in case of Uniprocessor machine, what happens if interrupts are generated while spinlock_irq_save() etc? TIA, Rick -- To unsub

Copy-on-Write

Hi, I had read that the operating systems that use copy-on-write mechanism for fork(), it is better if they deliberately allow the CHILD to run first. This would be better because in 99% of the cases child will call exec() and the new address space will be allocated. Instead if the parent is exec

TLB Question

Hi, I'm trying to understand the MMU operations & am wondering where is the kernel code where the kernel interfaces with the this piece of hardware? Can some one help me in understanding that what all are the responsibilities of the kernel, and what is it the hardware takes care of automatically?

Porting linux kernel on Xilinx FPGA board

Hi, I need to port a customized linux kernel on the latest Xilinx Virtex-5 FPGA based board (PowerPC architecture). However, my question relates more to the Xilinx FPGA technology (EDK etc.) than the kernel. Considering that this is a completely new board, what all EDK related things I'll need to