* [Qemu-devel] TARGET_PAGE_BITS
@ 2017-06-23 14:13 ali saeedi
2017-06-23 14:41 ` Alex Bennée
0 siblings, 1 reply; 6+ messages in thread
From: ali saeedi @ 2017-06-23 14:13 UTC (permalink / raw)
To: qemu-devel
Hello
What does TARGET_PAGE_BITS mean in qemu code?
thanks a lot
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] TARGET_PAGE_BITS
2017-06-23 14:13 [Qemu-devel] TARGET_PAGE_BITS ali saeedi
@ 2017-06-23 14:41 ` Alex Bennée
2017-06-23 15:02 ` ali saeedi
0 siblings, 1 reply; 6+ messages in thread
From: Alex Bennée @ 2017-06-23 14:41 UTC (permalink / raw)
To: ali saeedi; +Cc: qemu-devel
ali saeedi <ali.saeedi56@gmail.com> writes:
> Hello
> What does TARGET_PAGE_BITS mean in qemu code?
It's the page size of the target. e.g.
TARGET_PAGE_BITS 12
1 << 12 = 4096 = 4k pages
> thanks a lot
--
Alex Bennée
^ permalink raw reply [flat|nested] 6+ messages in thread
* Re: [Qemu-devel] TARGET_PAGE_BITS
2017-06-23 14:41 ` Alex Bennée
@ 2017-06-23 15:02 ` ali saeedi
2017-06-23 15:06 ` Peter Maydell
0 siblings, 1 reply; 6+ messages in thread
From: ali saeedi @ 2017-06-23 15:02 UTC (permalink / raw)
To: Alex Bennée; +Cc: qemu-devel
thank you for answer
So. why do we have right shift in qemu by "TARGET_PAGE_BITS" ? for exampe
in below code, what does it mean?
static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start,
ram_addr_t length)
{
unsigned long end, page;
end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
page = start >> TARGET_PAGE_BITS;
...
}
thanks a lot
On Fri, Jun 23, 2017 at 7:11 PM, Alex Bennée <alex.bennee@linaro.org> wrote:
>
> ali saeedi <ali.saeedi56@gmail.com> writes:
>
> > Hello
> > What does TARGET_PAGE_BITS mean in qemu code?
>
> It's the page size of the target. e.g.
>
> TARGET_PAGE_BITS 12
>
> 1 << 12 = 4096 = 4k pages
>
>
> > thanks a lot
>
>
> --
> Alex Bennée
>
^ permalink raw reply [flat|nested] 6+ messages in thread* Re: [Qemu-devel] TARGET_PAGE_BITS
2017-06-23 15:02 ` ali saeedi
@ 2017-06-23 15:06 ` Peter Maydell
0 siblings, 0 replies; 6+ messages in thread
From: Peter Maydell @ 2017-06-23 15:06 UTC (permalink / raw)
To: ali saeedi; +Cc: Alex Bennée, QEMU Developers
On 23 June 2017 at 16:02, ali saeedi <ali.saeedi56@gmail.com> wrote:
> thank you for answer
> So. why do we have right shift in qemu by "TARGET_PAGE_BITS" ? for exampe
> in below code, what does it mean?
>
> static inline void cpu_physical_memory_set_dirty_range(ram_addr_t start,
> ram_addr_t length)
> {
> unsigned long end, page;
>
> end = TARGET_PAGE_ALIGN(start + length) >> TARGET_PAGE_BITS;
> page = start >> TARGET_PAGE_BITS;
> ...
> }
If you take an address, and you shift it right by the number
of bits in a page, you get a page number...
thanks
-- PMM
^ permalink raw reply [flat|nested] 6+ messages in thread
* [Qemu-devel] TARGET_PAGE_BITS
@ 2017-05-22 12:54 ali saeedi
2017-05-22 13:10 ` Thomas Huth
0 siblings, 1 reply; 6+ messages in thread
From: ali saeedi @ 2017-05-22 12:54 UTC (permalink / raw)
To: qemu-devel
Hello
What is TARGET_PAGE_BITS in ram.c?
thanks a lot
^ permalink raw reply [flat|nested] 6+ messages in thread
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2017-06-23 14:13 [Qemu-devel] TARGET_PAGE_BITS ali saeedi
2017-06-23 14:41 ` Alex Bennée
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2017-06-23 15:06 ` Peter Maydell
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2017-05-22 13:10 ` Thomas Huth
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