[PATCH] makedumpfile: Enable compressed dump formats for Xen

[Atsushi Kumagai]

>> Hello Petr,
>>
>> >Hello all,
>> >
>> >this patch enables compressed file formats for Xen. I was suprized
>> >that nobody noticed earlier, given how trivial the change is. ;-)
>>
>> Good catch.
>> Since there is no Xen dump in the kdump-compressed format, is it also
>> necessary to fix the crash ?
>
>Yes, I have a patch set for crash, but I wanted to make sure the change
>gets accepted in makedumpfile first. The crash patch set is rather
>intrusive; if makedumpfile can actually produce such files, it makes it
>easier for me to negotiate with Dave Anderson. ;-)

I see, I think it's a good approach.

>> BTW, I think we should fix the manuals as well. There are some wrong
>> statements "-E option must be specified with this option" and
>> some examples implicate that -E option is necessary to Xen dump.
>
>Good point. Should I send it as a separate patch, or include it in a
>patch set and resend?

I prefer a separate patch, but I don't mind either way.


Thanks
Atsushi Kumagai

>Petr T
>
>> Thanks
>> Atsushi Kumagai
>>
>> >Originally, the compressed KDUMP format was not sufficient for Xen
>> >Dom0 dumps, because it did not contain required Xen-specific
>> >information. However, all this info is stored in ELF notes, which
>> >have been present in the compressed file since version 4, so there
>> >is no longer any reason to restrict Xen dumps to ELF only.
>> >
>> >One minor fix is necessary. In a Xen dump, PFN refers to physical
>> >pages _inside_ Dom0, but when compressing the whole file, the machine
>> >pages are used in fact (although the variable is still called pfn).
>> >Consequently, readmem() must interpret the address as a machine
>> >address rather than Dom0 physical address when saving Xen files.
>> >
>> >Signed-off-by: Petr Tesarik <ptesarik at suse.com>
>> >
>> >diff --git a/makedumpfile.c b/makedumpfile.c
>> >index de40932..2636036 100644
>> >--- a/makedumpfile.c
>> >+++ b/makedumpfile.c
>> >@@ -6015,9 +6015,11 @@ int
>> > read_pfn(mdf_pfn_t pfn, unsigned char *buf)
>> > {
>> > 	unsigned long long paddr;
>> >+	int type_addr;
>> >
>> > 	paddr = pfn_to_paddr(pfn);
>> >-	if (!readmem(PADDR, paddr, buf, info->page_size)) {
>> >+	type_addr = is_xen_memory() ? MADDR_XEN : PADDR;
>> >+	if (!readmem(type_addr, paddr, buf, info->page_size)) {
>> > 		ERRMSG("Can't get the page data.\n");
>> > 		return FALSE;
>> > 	}
>> >@@ -7654,12 +7656,6 @@ initial_xen(void)
>> > 	MSG("Xen is not supported on powerpc.\n");
>> > 	return FALSE;
>> > #else
>> >-	if(!info->flag_elf_dumpfile && !info->flag_dmesg) {
>> >-		MSG("Specify '-E' option for Xen.\n");
>> >-		MSG("Commandline parameter is invalid.\n");
>> >-		MSG("Try `makedumpfile --help' for more
>> >information.\n");
>> >-		return FALSE;
>> >-	}
>> > #ifndef __x86_64__
>> > 	if (DL_EXCLUDE_ZERO < info->max_dump_level) {
>> > 		MSG("Dump_level is invalid. It should be 0 or
>> > 1.\n");
>>
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