Re: [PATCH v7u1 00/31] x86, boot, 64bit: Add support for loadingramdisk and bzImage above 4G

From: Stefano Stabellini
Date: Wed Jan 16 2013 - 06:32:36 EST


On Tue, 15 Jan 2013, Yinghai Lu wrote:
> On Tue, Jan 15, 2013 at 8:43 AM, Yinghai Lu <yinghai@xxxxxxxxxx> wrote:
> > On Tue, Jan 15, 2013 at 4:19 AM, Stefano Stabellini
> > <stefano.stabellini@xxxxxxxxxxxxx> wrote:
> >>> could be found at:
> >>>
> >>> git://git.kernel.org/pub/scm/linux/kernel/git/yinghai/linux-yinghai.git for-x86-boot
> >>
> >> I tried to boot this kernel as PV guest with 2GB of RAM, but
> >> unfortunately it crashes early on at boot (earlyprintk=xen log
> >> appended).
> >>
> >>
> >>
> >> mapping kernel into physical memory
> >> about to get started...
> >> [ 0.000000] Initializing cgroup subsys cpuset
> >> [ 0.000000] Linux version 3.8.0-rc3+ (sstabellini@st22) (gcc version 4.4.5 (Debian 4.4.5-8) ) #4 SMP Tue Jan 15 12:11:59 UTC 2013
> >> [ 0.000000] Command line: root=/dev/xvda1 rw loglevel=9 debug console=hvc0 earlyprintk=xen
> >> [ 0.000000] ACPI in unprivileged domain disabled
> >> [ 0.000000] e820: BIOS-provided physical RAM map:
> >> [ 0.000000] Xen: [mem 0x0000000000000000-0x000000000009ffff] usable
> >> [ 0.000000] Xen: [mem 0x00000000000a0000-0x00000000000fffff] reserved
> >> [ 0.000000] Xen: [mem 0x0000000000100000-0x000000007fffffff] usable
> >> [ 0.000000] bootconsole [xenboot0] enabled
> >> [ 0.000000] NX (Execute Disable) protection: active
> >> [ 0.000000] DMI not present or invalid.
> >> [ 0.000000] e820: update [mem 0x00000000-0x0000ffff] usable ==> reserved
> >> [ 0.000000] e820: remove [mem 0x000a0000-0x000fffff] usable
> >> [ 0.000000] No AGP bridge found
> >> [ 0.000000] e820: last_pfn = 0x80000 max_arch_pfn = 0x400000000
> >> [ 0.000000] Base memory trampoline at [ffff88000009a000] 9a000 size 24576
> >> [ 0.000000] init_memory_mapping: [mem 0x00000000-0x000fffff]
> >> [ 0.000000] [mem 0x00000000-0x000fffff] page 4k
> >> [ 0.000000] init_memory_mapping: [mem 0x7fe00000-0x7fffffff]
> >> [ 0.000000] [mem 0x7fe00000-0x7fffffff] page 4k
> >> [ 0.000000] BRK [0x023b8000, 0x023b8fff] PGTABLE
> >> [ 0.000000] BRK [0x023b9000, 0x023b9fff] PGTABLE
> >> [ 0.000000] init_memory_mapping: [mem 0x7c000000-0x7fdfffff]
> >> [ 0.000000] [mem 0x7c000000-0x7fdfffff] page 4k
> >> [ 0.000000] BRK [0x023ba000, 0x023bafff] PGTABLE
> >> [ 0.000000] BRK [0x023bb000, 0x023bbfff] PGTABLE
> >> [ 0.000000] BRK [0x023bc000, 0x023bcfff] PGTABLE
> >> [ 0.000000] init_memory_mapping: [mem 0x00100000-0x7bffffff]
> >> [ 0.000000] [mem 0x00100000-0x7bffffff] page 4k
> >> (XEN) d15:v0: unhandled page fault (ec=0000)
> >> (XEN) Pagetable walk from ffffea0000080330:
> >> (XEN) L4[0x1d4] = 0000000000000000 ffffffffffffffff
> >> (XEN) domain_crash_sync called from entry.S
> >> (XEN) Domain 15 (vcpu#0) crashed on cpu#3:
> >> (XEN) ----[ Xen-4.3-unstable x86_64 debug=y Not tainted ]----
> >
> > ok, i think i know the cause for now, will check if there is good way
> > to fix it.
>
> Can you please test attached patch?

Yes, this patch seems to fix the problem.
I have also run the kernel with this patch as dom0 and PV domU with
various memory configurations up to 8GB, and I have no errors to report.
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