Hi Lennart, Do you have any idea that UBIFS supports writable memory mappings or not?
Regards, Karnik Jain On Wed, May 22, 2019 at 12:05 AM Kay One <kayone...@gmail.com> wrote: > Thank you so much for your time. > Let me try changing JFFS2 to UBIFS as another available option to use for > my SOC. > > I would keep you guys posted. > > Regards, > Karnik Jain > > On Tue, May 21, 2019 at 8:18 PM Lennart Poettering <lenn...@poettering.net> > wrote: > >> On Di, 21.05.19 17:37, Kay One (kayone...@gmail.com) wrote: >> >> > Thanks for the reply Lennart. >> > >> > 1) mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_SHARED, 28, 0) = -1 >> EINVAL >> > > (Invalid argument) is the culprit for this error??? >> >> Yes. >> >> > 2) If YES. Is this JFFS2 MTD file system bug or >> >> It's a missing feature of the fs implementation, that the journal >> relies on. Memory mapping a file is not a particularly exotic feature, >> and yes, file systems really should implement that. >> >> So my recommendation would be: work with the jffs2 folks to add this >> to the kernel. They already have it for PROT_READ afaik, doing it for >> PROT_WRITE is extra work, and not trivial but it will fix jffs2 for >> every program that uses mmap for writing, and journald is just one of >> them. >> >> > 3) Is this not considered as systemd bug to support compatibility for >> such >> > file system? Check first FS support writable mappings or not and if not >> > then use other method to enable Persistence logging for systemd? >> >> I think it's better to fix jffs2 in this regard than to add a >> userspace workaround to every single consumer of it. >> >> Doing this without mmap() is not trivial, and I don't see anyone >> stepping up to do the work. It wouldn't precisely make our codebase >> easier to read either... >> >> Lennart >> >> -- >> Lennart Poettering, Berlin >> >
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