[GSoC - x86_64] Clock driver - which hardware source to support primarily?

[Gedare Bloom]

On Wed, Jul 18, 2018 at 10:17 AM, Joel Sherrill <joel at rtems.org> wrote:
>
>
> On Wed, Jul 18, 2018 at 12:31 AM, Sebastian Huber
> <sebastian.huber at embedded-brains.de> wrote:
>>
>> Hello Amaan,
>>
>> On 17/07/18 19:18, Amaan Cheval wrote:
>>>
>>> Hi!
>>>
>>> Now that I'm working on the clock driver, we need to pick what we
>>> support first. Our options in brief are:
>>
>>
>> The clock driver needs an interrupt. What is the status of the interrupt
>> controller support in the BSP?
>>
>> For timekeeping we use a port of the FreeBSD timecounter in RTEMS. You may
>> have a look at the FreeBSD timecounter for this architecture, e.g.
>> sys/x86/x86/tsc.c. I looks quite complicated. I would not take to much care
>> about legacy support, e.g. ignore hardware which is older than five years?.
>
>
> That's not a good rule for PCs at all. The APIC was first introduced as an
> external controller with the i486,
> Based on your rule, we wouldn't support it even though it is the most likely
> choice.
>

I believe he meant ignore hardware that is not available from products
in the last five years.


> Avoid things that are deemed legacy. The starting point for this is the old
> PC
> System Design Guide.
>
> https://en.wikipedia.org/wiki/PC_System_Design_Guide
>
> If it was deemed obsolete in PC2001, then you definitely want to avoid it.
> Those
> things are just now really disappearing.
>

This is consistent with my interpretation.

> --joel
>
>>
>>
>>
>> --
>> Sebastian Huber, embedded brains GmbH
>>
>> Address : Dornierstr. 4, D-82178 Puchheim, Germany
>> Phone   : +49 89 189 47 41-16
>> Fax     : +49 89 189 47 41-09
>> E-Mail  : sebastian.huber at embedded-brains.de
>> PGP     : Public key available on request.
>>
>> Diese Nachricht ist keine geschäftliche Mitteilung im Sinne des EHUG.
>>
>