[PATCH v4 2/4] x86: Store memory ranges globally used for crash kernel to boot into

[Dave Young]

On 03/28/14 at 02:13pm, WANG Chao wrote:
> On 03/28/14 at 11:24am, Dave Young wrote:
> > >  
> > > +static void exclude_ram(struct memory_range *mr, int *nr_mr)
> > > +{
> > > +	int ranges, i, j, m;
> > > +
> > > +	ranges = *nr_mr;
> > > +	for (i = 0, j = 0; i < ranges; i++) {
> > > +		if (mr[j].type == RANGE_RAM) {
> > > +			dbgprintf("Remove RAM %016llx-%016llxx: (%d)\n", mr[j].start, mr[j].end, mr[j].type);
> > > +			for (m = j; m < *nr_mr; m++)
> > > +				mr[m] = mr[m+1];
> > > +			(*nr_mr)--;
> > > +		} else {
> > > +			j++;
> > > +		}
> > > +	}
> > > +
> > > +	dbgprint_mem_range("After remove RAM", mr, *nr_mr);
> > > +}
> > 
> > This is probably not necessary, what I understand you are doing is below:
> > 
> > get_crash_memory_ranges()
> >  -> collect all SYSTEM_RAM, ACPI, ACPI_NVS ranges, exclude crash reserved ranges.
> >  -> the system ram ranges are used to create elf header
> >  -> the ACPI, ACPI_NVS ranges are used by cmdline_add_memmap_acpi etc.
> 
> Yes.
> 
> > 
> > memmap_p
> >  -> contains all the crash reserved ranges
> >  -> to be used by cmdline_add_memmap
> 
> There's no memmap_p. I'll reuse crash_memory_ranges structure to store
> crash reserved ranges, ACPI and ACPI_NVS ranges. So after building ELF
> headers for 1st kernel memory ranges, all I have to do is exclude the
> SYSTEM_RAM and add crash_reserved to crash_memory_ranges. And then
> crash_memory_ranges can be used as 2nd kernel memory ranges.

How about do nothing and directly use the mem_ranges:
 * skip RANGE_RAM, only add the range which is not RANGE_RAM
 * if the range is RANGE_CRASH_KERNEL (introduce a new type?) then use it as SYSTEM_RAM for 2nd kernel.

> 
> > 
> > The several memory ranges are twisted and somehow the funcions are duplicate.
> 
> These functions look like similar but each does serve for different purpose.
> 
> > 
> > So how about just keep one memory ranges array which contains all the ranges which
> > include system_ram, acpi, acpi_nvs, crash_reserved range.
> > 
> > In the crashdump-elf.c the function for creating elf headers will check the
> > range type, it will just skip the range which is not ram.
> 
> We don't build EFL headers for crash_reserved ranges. So we can't store
> system ram and crash_reserved together before building EFL header.

There's already below code which ignore the ram ranges..
        for (i = 0; i < ranges; i++, range++) {
		if (range->type != RANGE_RAM)
			continue;

Thanks
Dave