Hi Robert,
Robert Millan <[EMAIL PROTECTED]> writes:
You forgot the changelog entry :-)
> On Sun, Aug 03, 2008 at 09:48:16PM +0200, Robert Millan wrote:
>> On Mon, Jul 28, 2008 at 10:05:33AM -0700, Colin D Bennett wrote:
>> > +/* Calibrate the TSC based on the RTC. */
>> > +static void
>> > +calibrate_tsc (void)
>> > +{
>> > + /* First calbrate the TSC rate (relative, not absolute time). */
>> > + grub_uint64_t start_tsc;
>> > + grub_uint64_t end_tsc;
>> > + grub_uint32_t initial_tick;
>> > + grub_uint32_t start_tick;
>> > + grub_uint32_t end_tick;
>> > +
>> > + /* Wait for the start of the next tick;
>> > + we'll base out timing off this edge. */
>> > + initial_tick = grub_get_rtc ();
>>
>> Ah, I see the problem. It calls grub_get_rtc() which in grub-coreboot is
>> just
>> a stub.
>>
>> How about using the interval timer for calibration instead?
>
> Here. With this patch your code works on coreboot too.
>
> Note: AFAICT we can't calculate the epoch without RTC. But then again, this
> epoch is just as defined by the time BIOS enables RTC interrupts, so why not
> define it ourselves? I propose that we define epoch as the time in which our
> TSC code is initialized.
>
> If knowing the time in which BIOS was started is really useful, maybe we could
> #ifdef it instead. Though if it's not I'd prefer the simplicity.
If this works and fixes coreboot, it is fine to me ;-)
One comment follows below.
> --- ../grub2.tsc/include/grub/i386/pit.h 1970-01-01 01:00:00.000000000
> +0100
> +++ ./include/grub/i386/pit.h 2008-08-04 01:22:12.000000000 +0200
> @@ -0,0 +1,19 @@
> +/*
> + * GRUB -- GRand Unified Bootloader
> + * Copyright (C) 2008 Free Software Foundation, Inc.
> + *
> + * GRUB is free software: you can redistribute it and/or modify
> + * it under the terms of the GNU General Public License as published by
> + * the Free Software Foundation, either version 3 of the License, or
> + * (at your option) any later version.
> + *
> + * GRUB is distributed in the hope that it will be useful,
> + * but WITHOUT ANY WARRANTY; without even the implied warranty of
> + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
> + * GNU General Public License for more details.
> + *
> + * You should have received a copy of the GNU General Public License
> + * along with GRUB. If not, see <http://www.gnu.org/licenses/>.
> + */
> +
> +extern void grub_pit_wait (grub_uint16_t tics);
Please us an inclusion guard.
--
Marco
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