Le 28/01/2020 à 04:33, Qian Cai a écrit :
On Jan 27, 2020, at 10:06 PM, Anshuman Khandual <anshuman.khandual@xxxxxxx> wrote: On 01/28/2020 07:41 AM, Qian Cai wrote:On Jan 27, 2020, at 8:28 PM, Anshuman Khandual <Anshuman.Khandual@xxxxxxx> wrote: This adds tests which will validate architecture page table helpers and other accessors in their compliance with expected generic MM semantics. This will help various architectures in validating changes to existing page table helpers or addition of new ones. This test covers basic page table entry transformations including but not limited to old, young, dirty, clean, write, write protect etc at various level along with populating intermediate entries with next page table page and validating them. Test page table pages are allocated from system memory with required size and alignments. The mapped pfns at page table levels are derived from a real pfn representing a valid kernel text symbol. This test gets called right after page_alloc_init_late(). This gets build and run when CONFIG_DEBUG_VM_PGTABLE is selected along with CONFIG_VM_DEBUG. Architectures willing to subscribe this test also need to select CONFIG_ARCH_HAS_DEBUG_VM_PGTABLE which for now is limited to x86 and arm64. Going forward, other architectures too can enable this after fixing build or runtime problems (if any) with their page table helpers.Hello Qian,What’s the value of this block of new code? It only supports x86 and arm64 which are supposed to be good now.We have been over the usefulness of this code many times before as the patch is already in it's V12. Currently it is enabled on arm64, x86 (except PAE), arc and ppc32. There are build time or runtime problems with other archs which preventI am not sure if I care too much about arc and ppc32 which are pretty much legacy platforms.enablement of this test (for the moment) but then the goal is to integrate all of them going forward. The test not only validates platform's adherence to the expected semantics from generic MM but also helps in keeping it that way during code changes in future as well.Another option maybe to get some decent arches on board first before merging this thing, so it have more changes to catch regressions for developers who might run this.
ppc32 an indecent / legacy platform ? Are you kidying ?Powerquicc II PRO for instance is fully supported by the manufacturer and widely used in many small networking devices.
Christophe
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