request_mem_region

request_mem_region

[Daniel Redway]

Hello

As I understand ioremap() maps and returns virtual address
for a given physical(bus) address associated with my PCI card.
That is cool and clear.


What is the purpose of request_mem_region()?
They both take physical address as a parameter, but do not return any
virt addresses.

1. What do they allocate/reserve and where?
2. Should I call reques_mem_region() before doing ioremap() or not?


thanks
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request_mem_region

[Mulyadi Santosa]

On 20/06/2011, Daniel Redway <daniel.redway85@gmail.com> wrote:
> Hello
>
> As I understand ioremap() maps and returns virtual address
> for a given physical(bus) address associated with my PCI card.
> That is cool and clear.
>
>
> What is the purpose of request_mem_region()?

checking http://lxr.linux.no/linux+v2.6.39/kernel/resource.c#L732, I
think that function generally says "alright,I wanna reserve this
memory region, so no one may touch it....until I mark it as free
again"

-- 
regards,

Mulyadi Santosa
Freelance Linux trainer and consultant

blog: the-hydra.blogspot.com
training: mulyaditraining.blogspot.com

request_mem_region

[Daniel Redway]

Ok I understood.
after I call request_mem_region , can real device write some byte to this
region?
or dont touch? I read mem region of device configuration space, start and
length register

thanks

2011/6/21 Mulyadi Santosa <mulyadi.santosa@gmail.com>

> On 20/06/2011, Daniel Redway <daniel.redway85@gmail.com> wrote:
> > Hello
> >
> > As I understand ioremap() maps and returns virtual address
> > for a given physical(bus) address associated with my PCI card.
> > That is cool and clear.
> >
> >
> > What is the purpose of request_mem_region()?
>
> checking http://lxr.linux.no/linux+v2.6.39/kernel/resource.c#L732, I
> think that function generally says "alright,I wanna reserve this
> memory region, so no one may touch it....until I mark it as free
> again"
>
> --
> regards,
>
> Mulyadi Santosa
> Freelance Linux trainer and consultant
>
> blog: the-hydra.blogspot.com
> training: mulyaditraining.blogspot.com
>
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