Re: [PATCH v2 0/2] Append new variables to vmcoreinfo (PTRS_PER_PGD for arm64 and MAX_PHYSMEM_BITS for all archs)
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 Cc: James Morse Cc: Will Deacon Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Michael Ellerman Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Dave Anderson Cc: Kazuhito Hagio Cc: x...@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-arm-ker...@lists.infradead.org Cc: linux-ker...@vger.kernel.org Cc: ke...@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
Re: [PATCH v2 0/2] Append new variables to vmcoreinfo (PTRS_PER_PGD for arm64 and MAX_PHYSMEM_BITS for all archs)
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 > Cc: James Morse > Cc: Will Deacon > Cc: Boris Petkov > Cc: Ingo Molnar > Cc: Thomas Gleixner > Cc: Michael Ellerman > Cc: Paul Mackerras > Cc: Benjamin Herrenschmidt > Cc: Dave Anderson > Cc: Kazuhito Hagio > Cc: x...@kernel.org > Cc: linuxppc-dev@lists.ozlabs.org > Cc: linux-arm-ker...@lists.infradead.org > Cc: linux-ker...@vger.kernel.org > Cc: ke...@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
[PATCH v2 0/2] Append new variables to vmcoreinfo (PTRS_PER_PGD for arm64 and MAX_PHYSMEM_BITS for all archs)
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 Cc: James Morse Cc: Will Deacon Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: Michael Ellerman Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Dave Anderson Cc: Kazuhito Hagio Cc: x...@kernel.org Cc: linuxppc-dev@lists.ozlabs.org Cc: linux-arm-ker...@lists.infradead.org Cc: linux-ker...@vger.kernel.org Cc: ke...@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(+) -- 2.7.4
