Date: Mon, 16 Mar 2015 19:58:10 -0300 From: =?UTF-8?Q?Mat=C3=ADas_Perret_Cantoni?= <perretcantonim@gmail.com> To: Thomas Skibo <thomasskibo@sbcglobal.net> Cc: freebsd-arm@freebsd.org Subject: Re: hexdumping /dev/mem Message-ID: <CADLKG02ugra2ToUH4t_oy3BLQU36dqdY761wtx3YqVSgG3vp8A@mail.gmail.com> In-Reply-To: <29227F8C-4A83-4C95-9CD2-BA14E797A882@sbcglobal.net> References: <CADLKG01HXRf9FE0JZ3hDdr6Ap-AbLM0r3TmhfLNOfwAUUqmbdA@mail.gmail.com> <29227F8C-4A83-4C95-9CD2-BA14E797A882@sbcglobal.net>
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2015-03-16 18:42 GMT-03:00 Thomas Skibo <thomasskibo@sbcglobal.net>: > >> On Mar 16, 2015, at 1:00 PM, Mat=C3=ADas Perret Cantoni <perretcantonim@= gmail.com> wrote: >> >> Hello! >> >> I'm trying to read a 32 bit register of the System Level Control >> Registers of the ZedBoard (Zynq-7000 SoC) from a running FreeBSD. I >> thought that I could simply do it with hexdump(1) to avoid writing a >> driver since I only need to read it once. I've tried: >> >> >> #hexdump -s 0xF8000910 -n 4 /dev/mem >> >> >> and I get this message: >> >> hexdump: /dev/mem: Invalid argument >> >> >> Reading some archives in this mailing list I've found that "the arm >> version of /dev/mem is not functionally equivalent to that of amd64 or >> i386. Arm disallows access to non-DRAM addresses through /dev/mem=E2=80= =9D. > > That=E2=80=99s correct. /dev/mem only reads from memory not devices. > > I always use kdb to peek/dump registers. You have to translate the devic= e addresses (use =E2=80=9Cshow devmap=E2=80=9D to see the mappings). > Looks like kdb is what I needed :). I don't even need hexdump. I guess I'm learning pretty basic stuff here. > But, once you know the kernel virtual addresses of the registers, you mig= ht be able to hexdump them through /dev/kmem. (I don=E2=80=99t have a Zedb= oard in front of me to try that.) > I couldn't find any man page for "kdb" or "db", and the help command of db didn't help much. ddb(4) and the section "On-Line Kernel Debugging Using DDB" of the developers-handbook were useful, but there's no clue about the show devmap there. Is there any other documentation source that I can read to find more about this? And last, once I entered kdb, is there any way to go back to the system without rebooting? Thank you! >> >> Is there any other way of doing this? Maybe the whole idea of using >> hexdump for this isn't really good. >> >> >> >> Thanks in advance. >> Regards, >> Matias. >> _______________________________________________ >> freebsd-arm@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-arm >> To unsubscribe, send any mail to "freebsd-arm-unsubscribe@freebsd.org" > > ------- > Thomas Skibo > thomasskibo@sbcglobal.net > > > >
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