| Message ID | 1552212242-9479-1-git-send-email-bhsharma@redhat.com (mailing list archive) |
|---|---|
| Headers | show |
| Series | Append new variables to vmcoreinfo (PTRS_PER_PGD for arm64 and MAX_PHYSMEM_BITS for all archs) | expand |
Hi Bhupesh, On 03/10/19 at 03:34pm, Bhupesh Sharma wrote: > Changes since v1: > ---------------- > - v1 was sent out as a single patch which can be seen here: > http://lists.infradead.org/pipermail/kexec/2019-February/022411.html > > - v2 breaks the single patch into two independent patches: > [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas > [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs) > > This patchset primarily fixes the regression reported in user-space > utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture > with the availability of 52-bit address space feature in underlying > kernel. These regressions have been reported both on CPUs which don't > support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels > and also on prototype platforms (like ARMv8 FVP simulator model) which > support ARMv8.2 extensions and are running newer kernels. > > The reason for these regressions is that right now user-space tools > have no direct access to these values (since these are not exported > from the kernel) and hence need to rely on a best-guess method of > determining value of 'PTRS_PER_PGD' and 'MAX_PHYSMEM_BITS' supported > by underlying kernel. > > Exporting these values via vmcoreinfo will help user-land in such cases. > In addition, as per suggestion from makedumpfile maintainer (Kazu) > during v1 review, it makes more sense to append 'MAX_PHYSMEM_BITS' to > vmcoreinfo in the core code itself rather than in arm64 arch-specific > code, so that the user-space code for other archs can also benefit from > this addition to the vmcoreinfo and use it as a standard way of > determining 'SECTIONS_SHIFT' value in user-land. > > Cc: Mark Rutland <mark.rutland@arm.com> > Cc: James Morse <james.morse@arm.com> > Cc: Will Deacon <will.deacon@arm.com> > Cc: Boris Petkov <bp@alien8.de> > Cc: Ingo Molnar <mingo@kernel.org> > Cc: Thomas Gleixner <tglx@linutronix.de> > Cc: Michael Ellerman <mpe@ellerman.id.au> > Cc: Paul Mackerras <paulus@samba.org> > Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> > Cc: Dave Anderson <anderson@redhat.com> > Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com> > Cc: x86@kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-arm-kernel@lists.infradead.org > Cc: linux-kernel@vger.kernel.org > Cc: kexec@lists.infradead.org > > Bhupesh Sharma (2): > arm64, vmcoreinfo : Append 'PTRS_PER_PGD' to vmcoreinfo > crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo > > arch/arm64/kernel/crash_core.c | 1 + > kernel/crash_core.c | 1 + > 2 files changed, 2 insertions(+) > Lianbo's document patch has been merged, would you mind to add vmcoreinfo doc patch as well in your series? Thanks Dave
Hi Dave, On 03/11/2019 02:35 PM, Dave Young wrote: > Hi Bhupesh, > On 03/10/19 at 03:34pm, Bhupesh Sharma wrote: >> Changes since v1: >> ---------------- >> - v1 was sent out as a single patch which can be seen here: >> http://lists.infradead.org/pipermail/kexec/2019-February/022411.html >> >> - v2 breaks the single patch into two independent patches: >> [PATCH 1/2] appends 'PTRS_PER_PGD' to vmcoreinfo for arm64 arch, whereas >> [PATCH 2/2] appends 'MAX_PHYSMEM_BITS' to vmcoreinfo in core kernel code (all archs) >> >> This patchset primarily fixes the regression reported in user-space >> utilities like 'makedumpfile' and 'crash-utility' on arm64 architecture >> with the availability of 52-bit address space feature in underlying >> kernel. These regressions have been reported both on CPUs which don't >> support ARMv8.2 extensions (i.e. LVA, LPA) and are running newer kernels >> and also on prototype platforms (like ARMv8 FVP simulator model) which >> support ARMv8.2 extensions and are running newer kernels. >> >> The reason for these regressions is that right now user-space tools >> have no direct access to these values (since these are not exported >> from the kernel) and hence need to rely on a best-guess method of >> determining value of 'PTRS_PER_PGD' and 'MAX_PHYSMEM_BITS' supported >> by underlying kernel. >> >> Exporting these values via vmcoreinfo will help user-land in such cases. >> In addition, as per suggestion from makedumpfile maintainer (Kazu) >> during v1 review, it makes more sense to append 'MAX_PHYSMEM_BITS' to >> vmcoreinfo in the core code itself rather than in arm64 arch-specific >> code, so that the user-space code for other archs can also benefit from >> this addition to the vmcoreinfo and use it as a standard way of >> determining 'SECTIONS_SHIFT' value in user-land. >> >> Cc: Mark Rutland <mark.rutland@arm.com> >> Cc: James Morse <james.morse@arm.com> >> Cc: Will Deacon <will.deacon@arm.com> >> Cc: Boris Petkov <bp@alien8.de> >> Cc: Ingo Molnar <mingo@kernel.org> >> Cc: Thomas Gleixner <tglx@linutronix.de> >> Cc: Michael Ellerman <mpe@ellerman.id.au> >> Cc: Paul Mackerras <paulus@samba.org> >> Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org> >> Cc: Dave Anderson <anderson@redhat.com> >> Cc: Kazuhito Hagio <k-hagio@ab.jp.nec.com> >> Cc: x86@kernel.org >> Cc: linuxppc-dev@lists.ozlabs.org >> Cc: linux-arm-kernel@lists.infradead.org >> Cc: linux-kernel@vger.kernel.org >> Cc: kexec@lists.infradead.org >> >> Bhupesh Sharma (2): >> arm64, vmcoreinfo : Append 'PTRS_PER_PGD' to vmcoreinfo >> crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo >> >> arch/arm64/kernel/crash_core.c | 1 + >> kernel/crash_core.c | 1 + >> 2 files changed, 2 insertions(+) >> > > Lianbo's document patch has been merged, would you mind to add vmcoreinfo doc > patch as well in your series? Thanks for the inputs. Will add it to the v3. Let's wait for other comments/reviews, before I spin a version 3. Regards, Bhupesh