On 10/30/19 10:08 AM, Kazuhito Hagio wrote:
Hi Bhupesh,
OK, thanks for letting me know that in your holidays. Have good ones.
I just thought that it might be good to share our understanding before
posting a kernel patch so that I can do something to support you if
need be.
Hi John,
You see that error with my test patch, which is only for testing though,
as I wrote below
Hi,
If there are corresponding kernel patches being considered to make
makedumpfile work on v8 and v8.x systems I would be interesting in
testing those also.
makedumpfile should be able to work with a variety of VAbits as 48, or
52 settings.
And wrote a very draft patch, which works on a 5.4-rc4 kernel that
I modified to have NUMBER(vabits_actual) and NUMBER(MAX_PHYSMEM_BITS),
that patch requires a kernel fix to have these in vmcoreinfo.
Did you try it?
Thanks,
Kazu
-----Original Message-----
Hi Kazu,
Sorry for top posting, but I am on leave for Diwali Holidays and will
return to the office in a couple of days.
I have the solution/patchset ready and I just need to finish the
commit messages to make sure they are self-explanatory for upstream
acceptance.
I will try to post them and also answer your email in detail when I
return back from holidays.
Thanks for your patience.
Regards,
Bhupesh
(Sent from my Android Phone)
On Tue, Oct 29, 2019 at 2:23 AM Kazuhito Hagio <k-hagio@xxxxxxxxxxxxx> wrote:
Hi Bhupesh,
-----Original Message-----
I am working on the changes in the vmcoreinfo after the 52-bit VA
changes from Steve were accepted in Linux 5.4-rc1 ("Support for 52-bit
virtual addressing in kernel space”).
I don’t see a commit with this title in linux-stable ; Could you be a little more specific what
file that was applied to ?
You can have a look at the following commit (and dependencies) in
Linus's tree (git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git)
which introduced 52-bit kernel VAs for arm64 architecture:
commit b6d00d47e81a49f6cf462518c10408f37a3e6785
Author: Steve Capper <steve.capper@xxxxxxx>
Date: Wed Aug 7 16:55:22 2019 +0100
arm64: mm: Introduce 52-bit Kernel VAs
Thank you for working on this.
I've also had a look at them, and my understanding is that we need
in vmcoreinfo at least:
- TCR_EL1.T1SZ (almost equals to vabits_actual) to determine:
o PAGE_OFFSET
o whether the kernel has the "flipped" linear map and the others.
We need a fix to __pa() with it. (see the patch below)
- PA_BITS or MAX_PHYSMEM_BITS to determine:
o whether SPARSEMEM_EXTREME or not, in is_sparsemem_extreme()
o whether the kernel has 48-bit or 52-bit PA to switch
the calculation of pte-to-paddr. (this might be unnecessary?)
Is this right?
And wrote a very draft patch, which works on a 5.4-rc4 kernel that
I modified to have NUMBER(vabits_actual) and NUMBER(MAX_PHYSMEM_BITS),
with VA_BITS=48 config or VA_BITS=52 config running in 48-bit mode.
https://urldefense.proofpoint.com/v2/url?u=https-3A__github.com_k-2Dhagio_makedumpfile_commit_fd9d86ea05b38e9edbb8c0ac3ebd612d5d485df3&d=DwIGaQ&c=RoP1YumCXCgaWHvlZYR8PZh8Bv7qIrMUB65eapI_JnE&r=t2fPg9D87F7D8jm0_3CG9yoiIKdRg4qc_thBw4bzMhc&m=D3owhCFsJR8X0Bhl0Tja3Jh5BFhvKkuKpiPnj9aZnZE&s=ZLnu3rvxqa6NPURmGNYpCG6g0H9yE3CCazQMWO40qOo&e=
(I don't intend to export them as they are, it's just for an experiment.
And no support for --mem-usage option, "real" 52-bit PA, and so on.)
As for MAX_PHYSMEM_BITS, I don't stick to export it for all architectures,
although I told you that it would be better to do so in the past.
If it's hard to do so, it's fine with me to export it or something similar
only for arm64 for now..
Your thoughts?
Thanks,
Kazu
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--
Thank You,
John
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