On Thu, 2026-10-01 at 09:42 +0100, Lorenzo Stoakes (ARM) wrote: > On Thu, Oct 01, 2026 at 09:08:33AM +0200, David Hildenbrand (Arm) wrote: > > On 9/30/26 01:57, Hajime Tazaki wrote: > > > Architectures lacking MMU don't support fork(2) syscall and only > > > vfork(2) is available with limitations. Thus, we cannot run kselftest > > > on nommu architecture as is. > > > > > > This commit addresses this issue with the following changes: > > > > > > - on test run stage, avoid calling timeout command when NOMMU=1 variable > > > added to environmental variable, since timeout command uses fork > > > syscall which nommu platform doesn't support. > > > - describe the difference of nommu tests in the document. > > > > > > So command line to build/execute tests for nommu should be like below: > > > > > > $ make ARCH=um NOMMU=1 O=build kselftest-all TARGETS=nommu > > > $ make ARCH=um NOMMU=1 O=build kselftest-install TARGETS=nommu > > > $ NOMMU=1 ./build/kselftest/kselftest_install/run_kselftest.sh -p \ > > > -c nommu > > > > Is there a way we could derive that from the environment in one of these > > cases? > > I thought maybe uname could help but our LLM overlords tell me no.
Hajime originally wanted uname to indicate it, but that caused regressions elsewhere, so we dropped that commit. I guess we could put _something_ back? > It pointed at something though. > > In fs/proc/meminfo.c: > > #ifndef CONFIG_MMU > show_val_kb(m, "MmapCopy: ", > (unsigned long)atomic_long_read(&mmap_pages_allocated)); > #endif > > So MmapCopy in /proc/meminfo tells us definitively, weirdly enough. Hyrum's law and all that, but I guess it's not highly likely to (want to) change :) johannes
