[Qemu-devel] Reading and writing functions for QEMU emulated peripherals

[Qemu-devel] Reading and writing functions for QEMU emulated peripherals

[Ramy Sameh]

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Hello all,

I was tracking the calling of function pl011_read, and I noticed that it is
called from function *memory_region_read_accessor *in memory.c

I also noticed that all peripherals reading functions (e.g. pl050_read,
pl190_read ... etc) in the emulated VersatilePB board, are called from the
same location in *memory_region_read_accessor.*

*My question is*: Is this calling procedure done for the emulated
VersatilePB board *only*, or this is the case for the peripherals in all
emulated systems ?

Thanks in advance for your support.

[image: Inline image 1]

-- 
Best Regards,
Ramy Sameh
Embedded Software Engineer
+2-010-172-777-14

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Re: [Qemu-devel] Reading and writing functions for QEMU emulated peripherals

[Peter Maydell]

On 15 October 2017 at 17:47, Ramy Sameh <ramysameh26@gmail.com> wrote:
> I was tracking the calling of function pl011_read, and I noticed that it is
> called from function *memory_region_read_accessor *in memory.c
>
> I also noticed that all peripherals reading functions (e.g. pl050_read,
> pl190_read ... etc) in the emulated VersatilePB board, are called from the
> same location in *memory_region_read_accessor.*
>
> *My question is*: Is this calling procedure done for the emulated
> VersatilePB board *only*, or this is the case for the peripherals in all
> emulated systems ?

Broadly speaking, yes, all peripheral device read and write
functions are invoked via the memory subsystem code (which
is the part of QEMU that figures out what memory region
covers whatever the physical address that the guest wrote
to is).

thanks
-- PMM

Re: [Qemu-devel] Reading and writing functions for QEMU emulated peripherals

[Ramy Sameh]

Many thanks Peter

On Sun, Oct 15, 2017 at 6:50 PM, Peter Maydell <peter.maydell@linaro.org>
wrote:

> On 15 October 2017 at 17:47, Ramy Sameh <ramysameh26@gmail.com> wrote:
> > I was tracking the calling of function pl011_read, and I noticed that it
> is
> > called from function *memory_region_read_accessor *in memory.c
> >
> > I also noticed that all peripherals reading functions (e.g. pl050_read,
> > pl190_read ... etc) in the emulated VersatilePB board, are called from
> the
> > same location in *memory_region_read_accessor.*
> >
> > *My question is*: Is this calling procedure done for the emulated
> > VersatilePB board *only*, or this is the case for the peripherals in all
> > emulated systems ?
>
> Broadly speaking, yes, all peripheral device read and write
> functions are invoked via the memory subsystem code (which
> is the part of QEMU that figures out what memory region
> covers whatever the physical address that the guest wrote
> to is).
>
> thanks
> -- PMM
>



-- 
Best Regards,
Ramy Sameh
Embedded Software Engineer
+2-010-172-777-14