Messages in this thread | | | Subject | Re: MIPS: bug: gettimeofday syscall broken on CI20 board | From | "H. Nikolaus Schaller" <> | Date | Thu, 28 Nov 2019 14:48:46 +0100 |
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> Am 28.11.2019 um 14:29 schrieb Maarten ter Huurne <maarten@treewalker.org>: > > On Thursday, 28 November 2019 13:33:17 CET H. Nikolaus Schaller wrote: >> Hi Vincenzo, >> >>> Am 28.11.2019 um 13:21 schrieb Vincenzo Frascino >>> <vincenzo.frascino@arm.com>:> >>> [...] >>> The the lib that provides the gettimeofday() changes accordingly >>> with vdso_data. 5.4 and 4.19 have 2 different vdso libraries as >>> well. >> >> Yes, that is what I have assumed what happens. How do these libs go >> into an existing and working root-file-system with Debian Stretch? > > I'm a novice when it comes to vDSO, so someone please correct me if I'm > wrong. > > From what I read vDSO is a library in the sense that it exports ELF > symbols that applications and other libraries (libc in particular) can > use, but it is not a file on disk.
Ah, ok. This would mean that the libc providing the gettimeofday() should be able to find out a modified changed vdso_data format by inspecting these ELF symbols.
> > As such, which rootfs you use shouldn't matter, since the vDSO is not in > the rootfs. Instead, it is contained in the kernel image. Searching for > "linux-vdso.so.1" on packages.debian.org indeed returns no hits. > > There is a check in arch/mips/vdso/Makefile that disables vDSO on MIPS > when building the kernel with binutils < 2.25. I don't know if that is > in any way related to this issue.
What still does not fit into the picture is the errno = 1 i.e. EPERM. Maybe I have to study the libc code that tries to read the ELF symbols you have mentioned. It may fail for unknown reasons.
BR and thanks, Nikolaus
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