Colin D Bennett <[EMAIL PROTECTED]> writes: > Hi Marco, > > On Thu, 03 Jul 2008 20:52:53 +0200 > Marco Gerards <[EMAIL PROTECTED]> wrote: > >> Hi Colin, >> >> Colin D Bennett <[EMAIL PROTECTED]> writes: >> >> > I have implemented high resolution time support (through the >> > new grub_get_time_ms() function) using the RDTSC instruction >> > available on Pentium and higher x86 CPUs. The TSC value is simply >> > a 64-bit block cycle counter that is zeroed at bootup, so >> > grub_main() calls grub_time_init(), which is defined by each >> > platform. If a platform links to kern/i386/tsc.c, then the >> > grub_time_init() function from tsc.c is used, which calibrates the >> > TSC rate and absolute zero reference using the RTC. >> What if TSC is not available? > > I updated the changelog entry to indicate that running on a 386 or 486 > will fail, since TSC is provided in Pentium+. Do we support running on > 386 or 386? Should I check for this? If so, the code will have to > change a bit, and be able to select between the generic implementation > and the TSC implementation at runtime. > > I think this would be best done letting the "grub_get_time_ms" > implementation be selected by setting a function pointer in > grub_machine_init() depending on the machine's capabilities. I would > have to significantly re-structure my patch, but it might be > necessary (and could lead to more understandable code?). > What do you think?
That would be great. I do not want to drop 486 support just because of this. You could even drop back to a lower granularity of the timer or better: submit code that does the trick for the 486 as well. -- Marco _______________________________________________ Grub-devel mailing list Grub-devel@gnu.org http://lists.gnu.org/mailman/listinfo/grub-devel
