Re: kexec, x86: Need a new e820 type support for kexec

Re: kexec, x86: Need a new e820 type support for kexec

[Baoquan He]

Hi Toshi,

Does this patch work for you?

There are things I am not sure. When jump to kexec/kdump kernel is this
PMEM still needed by system? And what's the difference between PRAM and
PMEM? I saw in kernel commit ec776ef6 it introduced E820_PRAM for the
non-standard protected e820 type, then in kernel commit ad5fb870 it
introduced E820_PMEM for ACPI 6.0 persistent memory types. While it
doesn't add complete support for E820_PMEM like E820_PRAM if I
understand it correctly. In this patch I simply pass E820_PMEM to kdump
kernel as E820_PRAM when it emerges since kernel can parse E820_PRAM
only in parse_memmap_one(), otherwise E820_PMEM has to be discarded or
need be passed as E820_RESERVED. What do you think about this, need
E820_PMEM be differentiated with E820_PRAM strictly? If yes, I think a
kernel patch need be posted to fix this. If not, this patch is enough
for supporting both of them in kexec.


>From 032f0c2cc89d1cde6d748b2cca90ebb829b4d589 Mon Sep 17 00:00:00 2001
From: Baoquan He <bhe@redhat.com>
Date: Thu, 25 Jun 2015 19:15:49 +0900
Subject: [PATCH] Add persistent memory support

Kernel add E820_PRAM or E820_PMEM type for NVDIMM memory device.
Now support them in kexec too.

Signed-off-by: Baoquan He <bhe@redhat.com>
---
 include/x86/x86-linux.h            |  2 ++
 kexec/arch/i386/crashdump-x86.c    | 10 +++++++++-
 kexec/arch/i386/kexec-x86-common.c | 10 ++++++++++
 kexec/arch/i386/x86-linux-setup.c  |  6 ++++++
 kexec/firmware_memmap.c            |  4 ++++
 kexec/kexec.h                      |  2 ++
 6 files changed, 33 insertions(+), 1 deletion(-)

diff --git a/include/x86/x86-linux.h b/include/x86/x86-linux.h
index 50c7324..7834751 100644
--- a/include/x86/x86-linux.h
+++ b/include/x86/x86-linux.h
@@ -21,6 +21,8 @@ struct e820entry {
 #define E820_RESERVED	2
 #define E820_ACPI	3 /* usable as RAM once ACPI tables have been read */
 #define E820_NVS	4
+#define E820_PMEM       7
+#define E820_PRAM       12
 } __attribute__((packed));
 #endif
 
diff --git a/kexec/arch/i386/crashdump-x86.c b/kexec/arch/i386/crashdump-x86.c
index 82bf239..dea42d0 100644
--- a/kexec/arch/i386/crashdump-x86.c
+++ b/kexec/arch/i386/crashdump-x86.c
@@ -301,6 +301,10 @@ static int get_crash_memory_ranges(struct memory_range **range, int *ranges,
 			type = RANGE_ACPI;
 		} else if(memcmp(str,"ACPI Non-volatile Storage\n",26) == 0 ) {
 			type = RANGE_ACPI_NVS;
+		} else if(memcmp(str,"Persistent Memory (legacy)\n",27) == 0 ) {
+			type = RANGE_PRAM;
+		} else if(memcmp(str,"Persistent Memory\n",18) == 0 ) {
+			type = RANGE_PMEM;
 		} else if(memcmp(str,"reserved\n",9) == 0 ) {
 			type = RANGE_RESERVED;
 		} else if (memcmp(str, "GART\n", 5) == 0) {
@@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char *cmdline, unsigned long startk,
 		strcat (str_mmap, "K$");
 	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
 		strcat (str_mmap, "K#");
+	else if (type == RANGE_PMEM || type == RANGE_PRAM)
+		strcat (str_mmap, "K!");
 
 	ultoa(startk, str_tmp);
 	strcat (str_mmap, str_tmp);
@@ -997,7 +1003,9 @@ int load_crashdump_segments(struct kexec_info *info, char* mod_cmdline,
 		unsigned long start, end, size, type;
 		if ( !( mem_range[i].type == RANGE_ACPI
 			|| mem_range[i].type == RANGE_ACPI_NVS
-			|| mem_range[i].type == RANGE_RESERVED))
+			|| mem_range[i].type == RANGE_RESERVED
+			|| mem_range[i].type == RANGE_PMEM
+			|| mem_range[i].type == RANGE_PRAM))
 			continue;
 		start = mem_range[i].start;
 		end = mem_range[i].end;
diff --git a/kexec/arch/i386/kexec-x86-common.c b/kexec/arch/i386/kexec-x86-common.c
index 3624192..90534a8 100644
--- a/kexec/arch/i386/kexec-x86-common.c
+++ b/kexec/arch/i386/kexec-x86-common.c
@@ -94,6 +94,12 @@ static int get_memory_ranges_proc_iomem(struct memory_range **range, int *ranges
 		else if (memcmp(str, "ACPI Non-volatile Storage\n", 26) == 0) {
 			type = RANGE_ACPI_NVS;
 		}
+		else if (memcmp(str, "Persistent Memory (legacy)\n", 27) == 0) {
+			type = RANGE_ACPI_NVS;
+		}
+		else if (memcmp(str, "Persistent Memory\n", 18) == 0) {
+			type = RANGE_ACPI_NVS;
+		}
 		else {
 			continue;
 		}
@@ -149,6 +155,10 @@ unsigned xen_e820_to_kexec_type(uint32_t type)
 			return RANGE_ACPI;
 		case E820_NVS:
 			return RANGE_ACPI_NVS;
+		case E820_PMEM:
+			return RANGE_PMEM;
+		case E820_PRAM:
+			return RANGE_PRAM;
 		case E820_RESERVED:
 		default:
 			return RANGE_RESERVED;
diff --git a/kexec/arch/i386/x86-linux-setup.c b/kexec/arch/i386/x86-linux-setup.c
index 9271c6c..c75adaa 100644
--- a/kexec/arch/i386/x86-linux-setup.c
+++ b/kexec/arch/i386/x86-linux-setup.c
@@ -705,6 +705,12 @@ static void add_e820_map_from_mr(struct x86_linux_param_header *real_mode,
 			case RANGE_ACPI_NVS:
 				e820[i].type = E820_NVS;
 				break;
+			case RANGE_PMEM:
+				e820[i].type = E820_PMEM;
+				break;
+			case RANGE_PRAM:
+				e820[i].type = E820_PRAM;
+				break;
 			default:
 			case RANGE_RESERVED:
 				e820[i].type = E820_RESERVED;
diff --git a/kexec/firmware_memmap.c b/kexec/firmware_memmap.c
index 6be3c7c..4d84f00 100644
--- a/kexec/firmware_memmap.c
+++ b/kexec/firmware_memmap.c
@@ -168,6 +168,10 @@ static int parse_memmap_entry(const char *entry, struct memory_range *range)
 		range->type = RANGE_ACPI_NVS;
 	else if (strcmp(type, "Uncached RAM") == 0)
 		range->type = RANGE_UNCACHED;
+	else if (strcmp(type, "Persistent Memory (legacy)") == 0)
+		range->type = RANGE_PRAM;
+	else if (strcmp(type, "Persistent Memory") == 0)
+		range->type = RANGE_PMEM;
 	else {
 		fprintf(stderr, "Unknown type (%s) while parsing %s. Please "
 			"report this as bug. Using RANGE_RESERVED now.\n",
diff --git a/kexec/kexec.h b/kexec/kexec.h
index b129c15..0fa977f 100644
--- a/kexec/kexec.h
+++ b/kexec/kexec.h
@@ -136,6 +136,8 @@ struct memory_range {
 #define RANGE_ACPI	2
 #define RANGE_ACPI_NVS	3
 #define RANGE_UNCACHED	4
+#define RANGE_PMEM		6
+#define RANGE_PRAM		11
 };
 
 struct memory_ranges {
-- 
2.1.0

Re: kexec, x86: Need a new e820 type support for kexec

[Toshi Kani]

On Thu, 2015-08-06 at 16:12 +0800, Baoquan He wrote:
> Hi Toshi,
> 
> Does this patch work for you?

Hi Baoquan,

I have tested the patch with both E820_PMEM and E820_PRAM setups, and
confirmed it works fine for both cases. :-)  I did multiple kexec reboots
followed by a kdump in my testing.  So, please feel free to add:
 
Tested-by: Toshi Kani <toshi.kani@hp.com>

> There are things I am not sure. When jump to kexec/kdump kernel is this
> PMEM still needed by system? 

Yes, after a kexec reboot, the kernel needs to be able to use NVDIMM as
before.  While the kernel actually uses NFIT table, not e820, the range
should be marked as PMEM for consistency.  The same goes to kdump kernel
since NVDIMM may be used as a dump device in future.

> And what's the difference between PRAM and
> PMEM? I saw in kernel commit ec776ef6 it introduced E820_PRAM for the
> non-standard protected e820 type, then in kernel commit ad5fb870 it
> introduced E820_PMEM for ACPI 6.0 persistent memory types. While it
> doesn't add complete support for E820_PMEM like E820_PRAM if I
> understand it correctly.

ACPI 6.0 spec defines E820_PMEM, which is used for NVDIMM devices from now
on.  ACPI 6.0 also defines NFIT table for NVDIMM along with this type.

Before these are defined in ACPI, E820_PRAM type was "unofficially" used by
some NVDIMM devices.  So, E820_PRAM was added for such legacy NVDIMMs. 
 Since the E820_PRAM case is very simple (it does not have any other FW
tables), it can be easily emulated with the "memmap=nn!ss" option.  So,
people may use the memmap option to emulate this legacy NVDIMM.    

>  In this patch I simply pass E820_PMEM to kdump
> kernel as E820_PRAM when it emerges since kernel can parse E820_PRAM
> only in parse_memmap_one(), otherwise E820_PMEM has to be discarded or
> need be passed as E820_RESERVED. What do you think about this, need
> E820_PMEM be differentiated with E820_PRAM strictly? If yes, I think a
> kernel patch need be posted to fix this. If not, this patch is enough
> for supporting both of them in kexec.

E820_PMEM cannot be emulated by the "memmap=" option.  Do you have to use
the "memmap=" options to pass the ranges for kdump kernel?  If so, I'd
rather ignore E820_PMEM and let it be passed as E820_RESERVED.  The kdump
kernel can still obtain the info from NFIT if necessary.

As for the code change...

> @@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char *cmdline, 
> unsigned long startk,
>  		strcat (str_mmap, "K$");
>  	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
>  		strcat (str_mmap, "K#");
> +	else if (type == RANGE_PMEM || type == RANGE_PRAM)
> +		strcat (str_mmap, "K!");

It should only check with RANGE_PRAM, but I do not think this change matters
much unless you also modify the caller cmdline_add_memmap(), which has the
following check to skip other types.  I do not think we will use legacy
NVDIMM device as a dump device, so you may ignore RANGE_PRAM and let it be
passed as RESERVED as well (which is likely the case I tested with).

                /* Only adding memory regions of RAM and ACPI */
                if (type != RANGE_RAM &&
                    type != RANGE_ACPI &&
                    type != RANGE_ACPI_NVS)
                        continue;

Thanks,
-Toshi

Re: kexec, x86: Need a new e820 type support for kexec

[Baoquan He]

Hi Toshi,

Sorry for replying late.

On 08/06/15 at 07:13pm, Toshi Kani wrote:
> On Thu, 2015-08-06 at 16:12 +0800, Baoquan He wrote:
> > Hi Toshi,
> > 
> > Does this patch work for you?
> 
> Hi Baoquan,
> 
> I have tested the patch with both E820_PMEM and E820_PRAM setups, and
> confirmed it works fine for both cases. :-)  I did multiple kexec reboots
> followed by a kdump in my testing.  So, please feel free to add:
>  
> Tested-by: Toshi Kani <toshi.kani@hp.com>

Thanks for testing, I will repost with Tested-by info.

> 
> > There are things I am not sure. When jump to kexec/kdump kernel is this
> > PMEM still needed by system? 
> 
> Yes, after a kexec reboot, the kernel needs to be able to use NVDIMM as
> before.  While the kernel actually uses NFIT table, not e820, the range
> should be marked as PMEM for consistency.  The same goes to kdump kernel
> since NVDIMM may be used as a dump device in future.
> 
> > And what's the difference between PRAM and
> > PMEM? I saw in kernel commit ec776ef6 it introduced E820_PRAM for the
> > non-standard protected e820 type, then in kernel commit ad5fb870 it
> > introduced E820_PMEM for ACPI 6.0 persistent memory types. While it
> > doesn't add complete support for E820_PMEM like E820_PRAM if I
> > understand it correctly.
> 
> ACPI 6.0 spec defines E820_PMEM, which is used for NVDIMM devices from now
> on.  ACPI 6.0 also defines NFIT table for NVDIMM along with this type.
> 
> Before these are defined in ACPI, E820_PRAM type was "unofficially" used by
> some NVDIMM devices.  So, E820_PRAM was added for such legacy NVDIMMs. 
>  Since the E820_PRAM case is very simple (it does not have any other FW
> tables), it can be easily emulated with the "memmap=nn!ss" option.  So,
> people may use the memmap option to emulate this legacy NVDIMM.    

I was wrong. In fact in kexec-tools memory info can be passed to kdump
kernel by 2 ways. One is using memmap by specifying
--pass-memmap-cmdline. The other one is storing memory regions in
e820_map of real mode data structure by default. And the 1st way is
rarely used. So no need to worry about the "memmap=nn!ss" option.

Since kernel parse_memmap_one doesn't support E820_PMEM well, I would
like to ignore the PMEM adding in memmap way. So this patch is enough.

> 
> >  In this patch I simply pass E820_PMEM to kdump
> > kernel as E820_PRAM when it emerges since kernel can parse E820_PRAM
> > only in parse_memmap_one(), otherwise E820_PMEM has to be discarded or
> > need be passed as E820_RESERVED. What do you think about this, need
> > E820_PMEM be differentiated with E820_PRAM strictly? If yes, I think a
> > kernel patch need be posted to fix this. If not, this patch is enough
> > for supporting both of them in kexec.
> 
> E820_PMEM cannot be emulated by the "memmap=" option.  Do you have to use
> the "memmap=" options to pass the ranges for kdump kernel?  If so, I'd
> rather ignore E820_PMEM and let it be passed as E820_RESERVED.  The kdump
> kernel can still obtain the info from NFIT if necessary.
> 
> As for the code change...
> 
> > @@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char *cmdline, 
> > unsigned long startk,
> >  		strcat (str_mmap, "K$");
> >  	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
> >  		strcat (str_mmap, "K#");
> > +	else if (type == RANGE_PMEM || type == RANGE_PRAM)
> > +		strcat (str_mmap, "K!");
> 
> It should only check with RANGE_PRAM, but I do not think this change matters
> much unless you also modify the caller cmdline_add_memmap(), which has the
> following check to skip other types.  I do not think we will use legacy
> NVDIMM device as a dump device, so you may ignore RANGE_PRAM and let it be
> passed as RESERVED as well (which is likely the case I tested with).
> 
>                 /* Only adding memory regions of RAM and ACPI */
>                 if (type != RANGE_RAM &&
>                     type != RANGE_ACPI &&
>                     type != RANGE_ACPI_NVS)
>                         continue;

Then if ignore PMEM adding into memmap, cmdline_add_memmap need not be
cared any more.

Thanks
Baoquan

Re: kexec, x86: Need a new e820 type support for kexec

[Toshi Kani]

On Tue, 2015-08-18 at 16:34 +0800, Baoquan He wrote:
> Hi Toshi,
> 
> Sorry for replying late.
> 
> On 08/06/15 at 07:13pm, Toshi Kani wrote:
> > On Thu, 2015-08-06 at 16:12 +0800, Baoquan He wrote:
> > > Hi Toshi,
> > > 
> > > Does this patch work for you?
> > 
> > Hi Baoquan,
> > 
> > I have tested the patch with both E820_PMEM and E820_PRAM setups, and
> > confirmed it works fine for both cases. :-)  I did multiple kexec 
> > reboots
> > followed by a kdump in my testing.  So, please feel free to add:
> >  
> > Tested-by: Toshi Kani <toshi.kani@hp.com>
> 
> Thanks for testing, I will repost with Tested-by info.
> 
> > 
> > > There are things I am not sure. When jump to kexec/kdump kernel is 
> > > this
> > > PMEM still needed by system? 
> > 
> > Yes, after a kexec reboot, the kernel needs to be able to use NVDIMM as
> > before.  While the kernel actually uses NFIT table, not e820, the range
> > should be marked as PMEM for consistency.  The same goes to kdump kernel
> > since NVDIMM may be used as a dump device in future.
> > 
> > > And what's the difference between PRAM and
> > > PMEM? I saw in kernel commit ec776ef6 it introduced E820_PRAM for the
> > > non-standard protected e820 type, then in kernel commit ad5fb870 it
> > > introduced E820_PMEM for ACPI 6.0 persistent memory types. While it
> > > doesn't add complete support for E820_PMEM like E820_PRAM if I
> > > understand it correctly.
> > 
> > ACPI 6.0 spec defines E820_PMEM, which is used for NVDIMM devices from 
> > now
> > on.  ACPI 6.0 also defines NFIT table for NVDIMM along with this type.
> > 
> > Before these are defined in ACPI, E820_PRAM type was "unofficially" used 
> > by
> > some NVDIMM devices.  So, E820_PRAM was added for such legacy NVDIMMs. 
> >  Since the E820_PRAM case is very simple (it does not have any other FW
> > tables), it can be easily emulated with the "memmap=nn!ss" option.  So,
> > people may use the memmap option to emulate this legacy NVDIMM.    
> 
> I was wrong. In fact in kexec-tools memory info can be passed to kdump
> kernel by 2 ways. One is using memmap by specifying
> --pass-memmap-cmdline. The other one is storing memory regions in
> e820_map of real mode data structure by default. And the 1st way is
> rarely used. So no need to worry about the "memmap=nn!ss" option.
> 
> Since kernel parse_memmap_one doesn't support E820_PMEM well, I would
> like to ignore the PMEM adding in memmap way. So this patch is enough.

Yes, that is fine.

> > >  In this patch I simply pass E820_PMEM to kdump
> > > kernel as E820_PRAM when it emerges since kernel can parse E820_PRAM
> > > only in parse_memmap_one(), otherwise E820_PMEM has to be discarded or
> > > need be passed as E820_RESERVED. What do you think about this, need
> > > E820_PMEM be differentiated with E820_PRAM strictly? If yes, I think a
> > > kernel patch need be posted to fix this. If not, this patch is enough
> > > for supporting both of them in kexec.
> > 
> > E820_PMEM cannot be emulated by the "memmap=" option.  Do you have to 
> > use the "memmap=" options to pass the ranges for kdump kernel?  If so, 
> > I'd rather ignore E820_PMEM and let it be passed as E820_RESERVED.  The
> > kdump kernel can still obtain the info from NFIT if necessary.
> > 
> > As for the code change...
> > 
> > > @@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char 
> > > *cmdline, 
> > > unsigned long startk,
> > >  		strcat (str_mmap, "K$");
> > >  	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
> > >  		strcat (str_mmap, "K#");
> > > +	else if (type == RANGE_PMEM || type == RANGE_PRAM)
> > > +		strcat (str_mmap, "K!");
> > 
> > It should only check with RANGE_PRAM, but I do not think this change 
> > matters much unless you also modify the caller cmdline_add_memmap(), 
> > which has the following check to skip other types.  I do not think we 
> > will use legacy NVDIMM device as a dump device, so you may ignore 
> > RANGE_PRAM and let it be passed as RESERVED as well (which is likely the > > case I tested with).
> > 
> >                 /* Only adding memory regions of RAM and ACPI */
> >                 if (type != RANGE_RAM &&
> >                     type != RANGE_ACPI &&
> >                     type != RANGE_ACPI_NVS)
> >                         continue;
> 
> Then if ignore PMEM adding into memmap, cmdline_add_memmap need not be
> cared any more.

Sounds good.

Thanks,
-Toshi

Re: kexec, x86: Need a new e820 type support for kexec

[Baoquan He]

On 08/06/15 at 07:13pm, Toshi Kani wrote:
> On Thu, 2015-08-06 at 16:12 +0800, Baoquan He wrote:
> E820_PMEM cannot be emulated by the "memmap=" option.  Do you have to use
> the "memmap=" options to pass the ranges for kdump kernel?  If so, I'd
> rather ignore E820_PMEM and let it be passed as E820_RESERVED.  The kdump
> kernel can still obtain the info from NFIT if necessary.
> 
> As for the code change...
> 
> > @@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char *cmdline, 
> > unsigned long startk,
> >  		strcat (str_mmap, "K$");
> >  	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
> >  		strcat (str_mmap, "K#");
> > +	else if (type == RANGE_PMEM || type == RANGE_PRAM)
> > +		strcat (str_mmap, "K!");
> 
> It should only check with RANGE_PRAM, but I do not think this change matters
> much unless you also modify the caller cmdline_add_memmap(), which has the
> following check to skip other types.  I do not think we will use legacy
> NVDIMM device as a dump device, so you may ignore RANGE_PRAM and let it be
> passed as RESERVED as well (which is likely the case I tested with).

Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
kernel if user really want to use memmap way by specifying
--pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
you pointed out. Will repost with them.


> 
>                 /* Only adding memory regions of RAM and ACPI */
>                 if (type != RANGE_RAM &&
>                     type != RANGE_ACPI &&
>                     type != RANGE_ACPI_NVS)
>                         continue;
> 

Re: kexec, x86: Need a new e820 type support for kexec

[Toshi Kani]

On Tue, 2015-08-18 at 16:53 +0800, Baoquan He wrote:
> On 08/06/15 at 07:13pm, Toshi Kani wrote:
> > On Thu, 2015-08-06 at 16:12 +0800, Baoquan He wrote:
> > E820_PMEM cannot be emulated by the "memmap=" option.  Do you have to 
> > use the "memmap=" options to pass the ranges for kdump kernel?  If so, 
> > I'd rather ignore E820_PMEM and let it be passed as E820_RESERVED.  The
> > kdump kernel can still obtain the info from NFIT if necessary.
> > 
> > As for the code change...
> > 
> > > @@ -640,6 +644,8 @@ static void cmdline_add_memmap_internal(char 
> > > *cmdline, 
> > > unsigned long startk,
> > >  		strcat (str_mmap, "K$");
> > >  	else if (type == RANGE_ACPI || type == RANGE_ACPI_NVS)
> > >  		strcat (str_mmap, "K#");
> > > +	else if (type == RANGE_PMEM || type == RANGE_PRAM)
> > > +		strcat (str_mmap, "K!");
> > 
> > It should only check with RANGE_PRAM, but I do not think this change 
> > matters much unless you also modify the caller cmdline_add_memmap(), 
> > which has the following check to skip other types.  I do not think we 
> > will use legacy NVDIMM device as a dump device, so you may ignore 
> > RANGE_PRAM and let it be passed as RESERVED as well (which is likely the 
> > case I tested with).
> 
> Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
> kernel if user really want to use memmap way by specifying
> --pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
> you pointed out. Will repost with them.

No, you should not report PMEM as PRAM.  They are different things.  The
kdump kernel does not need to support memmap cmdline for PMEM, as the
regular kernel does not -- memmap cmdline cannot emulate PMEM.

Thanks,
-Toshi


> 
> 
> > 
> >                 /* Only adding memory regions of RAM and ACPI */
> >                 if (type != RANGE_RAM &&
> >                     type != RANGE_ACPI &&
> >                     type != RANGE_ACPI_NVS)
> >                         continue;
> > 
> 

Re: kexec, x86: Need a new e820 type support for kexec

[Baoquan He]

On 08/18/15 at 09:01am, Toshi Kani wrote:
> On Tue, 2015-08-18 at 16:53 +0800, Baoquan He wrote:
> > Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
> > kernel if user really want to use memmap way by specifying
> > --pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
> > you pointed out. Will repost with them.
> 
> No, you should not report PMEM as PRAM.  They are different things.  The
> kdump kernel does not need to support memmap cmdline for PMEM, as the
> regular kernel does not -- memmap cmdline cannot emulate PMEM.

OK. Then it will be wrong if people intend to specify
--pass-memmap-cmdline. There might be 3 ways to fix this:

1) add PMEM support in kernel. memmap cmdline is not only used for
emulating, but for kexec/kdump using.

2) Delete --pass-memmap-cmdline option in kexec-tools since people
rarely use it.

3) Add a note in kexec-tools that option --pass-memmap-cmdline can't
work together with PMEM, people should not use it.

Thanks
Baoquan

Re: kexec, x86: Need a new e820 type support for kexec

[Toshi Kani]

On 8/18/2015 8:53 PM, Baoquan He wrote:
> On 08/18/15 at 09:01am, Toshi Kani wrote:
>> On Tue, 2015-08-18 at 16:53 +0800, Baoquan He wrote:
>>> Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
>>> kernel if user really want to use memmap way by specifying
>>> --pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
>>> you pointed out. Will repost with them.
>> No, you should not report PMEM as PRAM.  They are different things.  The
>> kdump kernel does not need to support memmap cmdline for PMEM, as the
>> regular kernel does not -- memmap cmdline cannot emulate PMEM.
> OK. Then it will be wrong if people intend to specify
> --pass-memmap-cmdline. There might be 3 ways to fix this:
>
> 1) add PMEM support in kernel. memmap cmdline is not only used for
> emulating, but for kexec/kdump using.
>
> 2) Delete --pass-memmap-cmdline option in kexec-tools since people
> rarely use it.
>
> 3) Add a note in kexec-tools that option --pass-memmap-cmdline can't
> work together with PMEM, people should not use it.

3) is fine, and I do not think we need a note either.  It does not make 
sense to add an memmap cmdline for PMEM since PMEM ranges require ACPI 
NFIT table.

Thanks,
-Toshi

Re: kexec, x86: Need a new e820 type support for kexec

[Baoquan He]

On 08/18/15 at 11:36pm, Toshi Kani wrote:
> On 8/18/2015 8:53 PM, Baoquan He wrote:
> >On 08/18/15 at 09:01am, Toshi Kani wrote:
> >>On Tue, 2015-08-18 at 16:53 +0800, Baoquan He wrote:
> >>>Rethink it again, maybe it's better to pass PMEM as PRAM to kdump
> >>>kernel if user really want to use memmap way by specifying
> >>>--pass-memmap-cmdline. Then I need add the PMEM and PRAM checking here
> >>>you pointed out. Will repost with them.
> >>No, you should not report PMEM as PRAM.  They are different things.  The
> >>kdump kernel does not need to support memmap cmdline for PMEM, as the
> >>regular kernel does not -- memmap cmdline cannot emulate PMEM.
> >OK. Then it will be wrong if people intend to specify
> >--pass-memmap-cmdline. There might be 3 ways to fix this:
> >
> >1) add PMEM support in kernel. memmap cmdline is not only used for
> >emulating, but for kexec/kdump using.
> >
> >2) Delete --pass-memmap-cmdline option in kexec-tools since people
> >rarely use it.
> >
> >3) Add a note in kexec-tools that option --pass-memmap-cmdline can't
> >work together with PMEM, people should not use it.
> 
> 3) is fine, and I do not think we need a note either.  It does not
> make sense to add an memmap cmdline for PMEM since PMEM ranges
> require ACPI NFIT table.

OK, got it. Let me repost without PMEM memmap adding. In fact I am
a little confused that E820_PMEM is got by EFI in linux, seems in
do_add_efi_memmap() though later ACPI NFIT need be read and more
information about nvdimm will be got for nvdimm device. e820 memory map
need be got from uefi/bios/kexec, this doesn't conflict with ACPI NFIT
processing.

Thanks
Baoquan