linux-kernel - Re: [PATCH] x86: extend e820 ealy_res support 32bit

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Message-ID: <4840225F.7010809@goop.org>
Date:	Fri, 30 May 2008 16:50:55 +0100
From:	Jeremy Fitzhardinge <jeremy@...p.org>
To:	Yinghai Lu <yhlu.kernel@...il.com>
CC:	Rusty Russell <rusty@...tcorp.com.au>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...e.hu>, "H. Peter Anvin" <hpa@...or.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] x86: extend e820 ealy_res support 32bit - fix #2

Yinghai Lu wrote:
> On Thu, May 29, 2008 at 11:52 AM, Yinghai Lu <yhlu.kernel@...il.com> wrote:
>   
>> On Thu, May 29, 2008 at 6:37 AM, Jeremy Fitzhardinge <jeremy@...p.org> wrote:
>>     
>>> Yinghai Lu wrote:
>>>       
>>>> can we use e820 entries for that? So the domain builder could have
>>>> several entries for E820_RAM and E820_RESERVED...
>>>>
>>>>         
>>> I tried this, but it doesn't work; the kernel crashes during boot,
>>> presumably because it's trying to use the reserved memory as heap.  I
>>> suspect the e820 maps are not registered early enough or something...
>>>
>>> (One thought: if reserving in the E820 map were enough, then couldn't we use
>>> it for all the early reservations?)
>>>
>>> I've attached the non-working patch below.
>>>
>>> The working kernel reports:
>>>
>>> (early) BIOS-provided physical RAM map:
>>> (early)  Xen: 0000000000000000 - 000000000009f000 (usable)
>>> (early)  Xen: 0000000000100000 - 0000000010000000 (usable)
>>> (early) console [xenboot0] enabled
>>> (early) debug: ignoring loglevel setting.
>>> (early) 0MB HIGHMEM available.
>>> (early) 256MB LOWMEM available.
>>> (early)   low ram: 018fd000 - 10000000
>>> (early)   bootmap 018fd000 - 018ff000
>>> (early)   early res: 0 [0-fff] BIOS data page
>>> (early)   early res: 1 [1000-1fff] EX TRAMPOLINE
>>> (early)   early res: 2 [6000-6fff] TRAMPOLINE
>>> (early)   early res: 3 [18aa000-18ecfff] XEN
>>> (early)   early res: 4 [1000000-18a9303] TEXT DATA BSS
>>> (early)   early res: 5 [18ed000-18fcfff] INIT_PG_TABLE
>>> (early)   early res: 6 [18fd000-18fefff] BOOTMAP
>>>
>>> But the non-working one says:
>>>
>>> (early) BIOS-provided physical RAM map:
>>> (early)  Xen: 0000000000000000 - 000000000009f000 (usable)
>>> (early)  Xen: 0000000000100000 - 0000000010000000 (usable)
>>> (early)  Xen: 00000000018aa000 - 00000000018ed000 (reserved)
>>>       
>> it seems we miss to call sanitize_e820_map for 32 bit. we should get
>> (early)  Xen: 0000000000000000 - 000000000009f000 (usable)
>> (early)  Xen: 0000000000100000 - 00000000018aa000 (usable)
>> (early)  Xen: 00000000018aa000 - 00000000018ed000 (reserved)
>> (early)  Xen: 00000000018ed000 - 0000000010000000 (usable)
>>     
>
> xen pv override the memory_setup. and default one is
> machine_specific_memory_setup(), and it does call sanitize_e820_map...
>
> so you may need to add sanitize_e820_map to xen_memory_setup, or re
> arrange your add_memory_range parameter...

Yes, adding

        sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);

after the Xen reservation made everything happy.

    J

Subject: xen: reserve Xen-specific memory in e820 map

Make sure that the start_info and pfn->mfn translation array are reserved.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@...rix.com>
---
 arch/x86/xen/setup.c |   13 +++++++++++++
 1 file changed, 13 insertions(+)

===================================================================
--- a/arch/x86/xen/setup.c
+++ b/arch/x86/xen/setup.c
@@ -40,8 +40,21 @@
 	max_pfn = min(MAX_DOMAIN_PAGES, max_pfn);
 
 	e820.nr_map = 0;
+
 	add_memory_region(0, LOWMEMSIZE(), E820_RAM);
 	add_memory_region(HIGH_MEMORY, PFN_PHYS(max_pfn)-HIGH_MEMORY, E820_RAM);
+
+	/*
+	 * Reserve Xen bits:
+	 *  - mfn_list
+	 *  - xen_start_info
+	 * See comment above "struct start_info" in <xen/interface/xen.h>
+	 */
+	add_memory_region(__pa(xen_start_info->mfn_list),
+			  xen_start_info->pt_base - xen_start_info->mfn_list,
+			  E820_RESERVED);
+
+	sanitize_e820_map(e820.map, ARRAY_SIZE(e820.map), &e820.nr_map);
 
 	return "Xen";
 }


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