Re: [PATCH v6 1/2] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
On Thu, Jul 02, 2020 at 08:08:55PM +0800, Dave Young wrote: > Hi Catalin, > On 07/02/20 at 12:00pm, Catalin Marinas wrote: > > On Thu, May 14, 2020 at 12:22:36AM +0530, Bhupesh Sharma wrote: > > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > > > index 9f1557b98468..18175687133a 100644 > > > --- a/kernel/crash_core.c > > > +++ b/kernel/crash_core.c > > > @@ -413,6 +413,7 @@ static int __init crash_save_vmcoreinfo_init(void) > > > VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); > > > VMCOREINFO_STRUCT_SIZE(mem_section); > > > VMCOREINFO_OFFSET(mem_section, section_mem_map); > > > + VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); > > > #endif > > > VMCOREINFO_STRUCT_SIZE(page); > > > VMCOREINFO_STRUCT_SIZE(pglist_data); > > > > I can queue this patch via the arm64 tree (together with the second one) > > but I'd like an ack from the kernel/crash_core.c maintainers. They don't > > seem to have been cc'ed either (only the kexec list). > > For the VMCOREINFO part, I'm fine with the changes, but since I do not > understand the arm64 pieces so I would like to leave to arm64 people to > review. If arm64 bits are good enough, feel free to add: > > Acked-by: Dave Young Thanks. -- Catalin
Re: [PATCH v6 1/2] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
Hi Catalin, On 07/02/20 at 12:00pm, Catalin Marinas wrote: > On Thu, May 14, 2020 at 12:22:36AM +0530, Bhupesh Sharma wrote: > > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > > index 9f1557b98468..18175687133a 100644 > > --- a/kernel/crash_core.c > > +++ b/kernel/crash_core.c > > @@ -413,6 +413,7 @@ static int __init crash_save_vmcoreinfo_init(void) > > VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); > > VMCOREINFO_STRUCT_SIZE(mem_section); > > VMCOREINFO_OFFSET(mem_section, section_mem_map); > > + VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); > > #endif > > VMCOREINFO_STRUCT_SIZE(page); > > VMCOREINFO_STRUCT_SIZE(pglist_data); > > I can queue this patch via the arm64 tree (together with the second one) > but I'd like an ack from the kernel/crash_core.c maintainers. They don't > seem to have been cc'ed either (only the kexec list). For the VMCOREINFO part, I'm fine with the changes, but since I do not understand the arm64 pieces so I would like to leave to arm64 people to review. If arm64 bits are good enough, feel free to add: Acked-by: Dave Young Thanks Dave
Re: [PATCH v6 1/2] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
On Thu, May 14, 2020 at 12:22:36AM +0530, Bhupesh Sharma wrote: > diff --git a/kernel/crash_core.c b/kernel/crash_core.c > index 9f1557b98468..18175687133a 100644 > --- a/kernel/crash_core.c > +++ b/kernel/crash_core.c > @@ -413,6 +413,7 @@ static int __init crash_save_vmcoreinfo_init(void) > VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); > VMCOREINFO_STRUCT_SIZE(mem_section); > VMCOREINFO_OFFSET(mem_section, section_mem_map); > + VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); > #endif > VMCOREINFO_STRUCT_SIZE(page); > VMCOREINFO_STRUCT_SIZE(pglist_data); I can queue this patch via the arm64 tree (together with the second one) but I'd like an ack from the kernel/crash_core.c maintainers. They don't seem to have been cc'ed either (only the kexec list). Thanks. -- Catalin
[PATCH v6 1/2] crash_core, vmcoreinfo: Append 'MAX_PHYSMEM_BITS' to vmcoreinfo
Right now user-space tools like 'makedumpfile' and 'crash' need to rely on a best-guess method of determining value of 'MAX_PHYSMEM_BITS' supported by underlying kernel. This value is used in user-space code to calculate the bit-space required to store a section for SPARESMEM (similar to the existing calculation method used in the kernel implementation): #define SECTIONS_SHIFT(MAX_PHYSMEM_BITS - SECTION_SIZE_BITS) Now, regressions have been reported in user-space utilities like 'makedumpfile' and 'crash' on arm64, with the recently added kernel support for 52-bit physical address space, as there is no clear method of determining this value in user-space (other than reading kernel CONFIG flags). As per suggestion from makedumpfile maintainer (Kazu), it makes more sense to append 'MAX_PHYSMEM_BITS' to vmcoreinfo in the core code itself rather than in 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. A reference 'makedumpfile' implementation which reads the 'MAX_PHYSMEM_BITS' value from vmcoreinfo in a arch-independent fashion is available here: While at it also update vmcoreinfo documentation for 'MAX_PHYSMEM_BITS' variable being added to vmcoreinfo. 'MAX_PHYSMEM_BITS' defines the maximum supported physical address space memory. Cc: Boris Petkov Cc: Ingo Molnar Cc: Thomas Gleixner Cc: James Morse Cc: Mark Rutland Cc: Will Deacon Cc: Michael Ellerman Cc: Paul Mackerras Cc: Benjamin Herrenschmidt Cc: Dave Anderson Cc: Kazuhito Hagio Cc: x...@kernel.org Cc: linuxppc-...@lists.ozlabs.org Cc: linux-arm-ker...@lists.infradead.org Cc: linux-kernel@vger.kernel.org Cc: ke...@lists.infradead.org Tested-by: John Donnelly Signed-off-by: Bhupesh Sharma --- Documentation/admin-guide/kdump/vmcoreinfo.rst | 5 + kernel/crash_core.c| 1 + 2 files changed, 6 insertions(+) diff --git a/Documentation/admin-guide/kdump/vmcoreinfo.rst b/Documentation/admin-guide/kdump/vmcoreinfo.rst index e4ee8b2db604..2a632020f809 100644 --- a/Documentation/admin-guide/kdump/vmcoreinfo.rst +++ b/Documentation/admin-guide/kdump/vmcoreinfo.rst @@ -93,6 +93,11 @@ It exists in the sparse memory mapping model, and it is also somewhat similar to the mem_map variable, both of them are used to translate an address. +MAX_PHYSMEM_BITS + + +Defines the maximum supported physical address space memory. + page diff --git a/kernel/crash_core.c b/kernel/crash_core.c index 9f1557b98468..18175687133a 100644 --- a/kernel/crash_core.c +++ b/kernel/crash_core.c @@ -413,6 +413,7 @@ static int __init crash_save_vmcoreinfo_init(void) VMCOREINFO_LENGTH(mem_section, NR_SECTION_ROOTS); VMCOREINFO_STRUCT_SIZE(mem_section); VMCOREINFO_OFFSET(mem_section, section_mem_map); + VMCOREINFO_NUMBER(MAX_PHYSMEM_BITS); #endif VMCOREINFO_STRUCT_SIZE(page); VMCOREINFO_STRUCT_SIZE(pglist_data); -- 2.7.4
