Re: [U-Boot] [PATCH 2/2] calimain: Generate random MAC address for factory tests
Dear Christian Riesch, In message <50ed2b84.2080...@omicron.at> you wrote: > > > What exactly is your justification for such a change? Please > > elucidate... > > Actually I do not change anything ;-) Why do you need a patch then? :-P > > NAK! You are but duplicating the code already present in net/eth.c > > Apparently I am missing something here. I do not see a call of > eth_random_enetaddr() in net/eth.c. To which part of net/eth.c are you > referring? Hm... I can't find it now, either. Dunno what I have seen then. eventually I was looking at your patch in two windows :-( Sorry - but still: very similar code exists in rescue_mode() in "board/buffalo/lsxl/lsxl.c"; this should be factored out. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de Any sufficiently advanced technology is indistinguishable from a rigged demo. - Andy Finkel, computer guy ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH 2/2] calimain: Generate random MAC address for factory tests
Hello Wolfgang, Thank you again for your comments. On 2013-01-08 18:39, Wolfgang Denk wrote: Dear Christian Riesch, In message <6cc4810c-1e2e-4ebf-912a-96936f035...@mary.at.omicron.at> you wrote: Signed-off-by: Christian Riesch --- board/omicron/calimain/calimain.c | 31 ++- include/configs/calimain.h|2 ++ 2 files changed, 32 insertions(+), 1 deletion(-) diff --git a/board/omicron/calimain/calimain.c b/board/omicron/calimain/calimain.c index 1060a1f..80e3893 100644 --- a/board/omicron/calimain/calimain.c +++ b/board/omicron/calimain/calimain.c @@ -1,5 +1,5 @@ /* - * Copyright (C) 2011 OMICRON electronics GmbH + * Copyright (C) 2011-2013 OMICRON electronics GmbH * * Based on da850evm.c. Original Copyrights follow: * @@ -136,6 +136,35 @@ int board_init(void) return 0; } +/* seed random number generator with uninitialized SRAM content */ +static void srand_sram(void) +{ + int *p; + int seed = 0; + + for (p = (int *) 0x8000; p < (int *) 0x8001; p++) + seed ^= *p; + + srand(seed); +} Note that your "uninitialized" SRAM content is probably not so much random at all - There are several papers around describing the use of initial SRAM value after power up for the generation of random numbers. This is why I gave it a try, and it works pretty well for me. I get a different seed for each power-up cycle. I guess that the randomness is limited and that part of the generated seed is more a fingerprint for the chip, therefore it may not be good enough for security related stuff, but for my purpose it's ok. I guess, it is much less random than the originally used timer value. In my case the timer value is not random at all since it is reset to zero at power-up. Since seeding the random number generator is always done at the same time after power-up in the current code, the seed will always be the same for my devices. Therefore the generated MAC address will always be the same for all devices. What exactly is your justification for such a change? Please elucidate... Actually I do not change anything ;-) For the lsxl board that is currently the only user of eth_random_enet(), nothing changes. get_timer(0) remains the source of the randomness for this board. My patches only allow other boards to use a sources of randomness that is available to them instead of forcing everyone to use get_timer(0). +int board_late_init(void) +{ + uchar enetaddr[6]; + + if (!eth_getenv_enetaddr("ethaddr", enetaddr)) { + srand_sram(); + eth_random_enetaddr(enetaddr); + if (eth_setenv_enetaddr("ethaddr", enetaddr)) { + printf("Failed to set random ethernet address\n"); + } else { + printf("Setting random ethernet address %pM.\n", + enetaddr); + } + } + return 0; +} NAK! You are but duplicating the code already present in net/eth.c Apparently I am missing something here. I do not see a call of eth_random_enetaddr() in net/eth.c. To which part of net/eth.c are you referring? Regards, Christian This makes no sense. Best regards, Wolfgang Denk ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
Re: [U-Boot] [PATCH 2/2] calimain: Generate random MAC address for factory tests
Dear Christian Riesch, In message <6cc4810c-1e2e-4ebf-912a-96936f035...@mary.at.omicron.at> you wrote: > Signed-off-by: Christian Riesch > --- > board/omicron/calimain/calimain.c | 31 ++- > include/configs/calimain.h|2 ++ > 2 files changed, 32 insertions(+), 1 deletion(-) > > diff --git a/board/omicron/calimain/calimain.c > b/board/omicron/calimain/calimain.c > index 1060a1f..80e3893 100644 > --- a/board/omicron/calimain/calimain.c > +++ b/board/omicron/calimain/calimain.c > @@ -1,5 +1,5 @@ > /* > - * Copyright (C) 2011 OMICRON electronics GmbH > + * Copyright (C) 2011-2013 OMICRON electronics GmbH > * > * Based on da850evm.c. Original Copyrights follow: > * > @@ -136,6 +136,35 @@ int board_init(void) > return 0; > } > > +/* seed random number generator with uninitialized SRAM content */ > +static void srand_sram(void) > +{ > + int *p; > + int seed = 0; > + > + for (p = (int *) 0x8000; p < (int *) 0x8001; p++) > + seed ^= *p; > + > + srand(seed); > +} Note that your "uninitialized" SRAM content is probably not so much random at all - I guess, it is much less random than the originally used timer value. What exactly is your justification for such a change? Please elucidate... > +int board_late_init(void) > +{ > + uchar enetaddr[6]; > + > + if (!eth_getenv_enetaddr("ethaddr", enetaddr)) { > + srand_sram(); > + eth_random_enetaddr(enetaddr); > + if (eth_setenv_enetaddr("ethaddr", enetaddr)) { > + printf("Failed to set random ethernet address\n"); > + } else { > + printf("Setting random ethernet address %pM.\n", > +enetaddr); > + } > + } > + return 0; > +} NAK! You are but duplicating the code already present in net/eth.c This makes no sense. Best regards, Wolfgang Denk -- DENX Software Engineering GmbH, MD: Wolfgang Denk & Detlev Zundel HRB 165235 Munich, Office: Kirchenstr.5, D-82194 Groebenzell, Germany Phone: (+49)-8142-66989-10 Fax: (+49)-8142-66989-80 Email: w...@denx.de It is dangerous to be right on a subject on which the established authorities are wrong.-- Voltaire ___ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot