Hi Tom, On Mon, Dec 3, 2012 at 5:59 AM, Tom Rini <tr...@ti.com> wrote: > -----BEGIN PGP SIGNED MESSAGE----- > Hash: SHA1 > > On 12/02/12 09:55, Simon Glass wrote: >> From: Gabe Black <gabebl...@chromium.org> >> >> The default implementation of this function is just memset, but >> other implementations will be needed when physical memory isn't >> accessible by U-Boot using normal addressing mechanisms. >> >> Signed-off-by: Gabe Black <gabebl...@chromium.org> Signed-off-by: >> Che-Liang Chiou <clch...@chromium.org> Signed-off-by: Simon Glass >> <s...@chromium.org> > > We've supported PowerPC platforms with 36bit memory ranges for ages. > Part of that however I believe is just not touching that high memory > range. So why do we need to touch the range here, rather than just > configuring the memory controller and booting Linux? Is this for some > hardware tester for example?
We need to clear all memory as part of the secure boot, to avoid attacks which involve leaving code around over a reboot, etc. For x86 also we avoid touching memory above 4GB during normal operation, but it isn't enough to just ignore it, since there might be something lurking there that someone can invoke. The support is minimal (just clearing it) and we don't want to start using it in any other way. Regards, Simon > > - -- > Tom > -----BEGIN PGP SIGNATURE----- > Version: GnuPG v1.4.11 (GNU/Linux) > Comment: Using GnuPG with Mozilla - http://www.enigmail.net/ > > iQIcBAEBAgAGBQJQvLBWAAoJENk4IS6UOR1WS3oP/3OslD0jJzixbYNn35N+4KjY > dgnkNuLYwiXPhsw9sRttNihf7C2XLfPtbJfQo97hAVSgULLgBjjRN4HtoB9Yx3M1 > hMtPcWzt/JxOOzgKwUBF1RdFwQ8ENmD0AYQ3F6D3uNq/3Tez9/VkrrXpbMnNvNyh > cw1fKT0aFDJgTdoK6KWRvXd1Z/cQk0+aWDFXhi1Y1yBag80PKXoiEATrd3hg1Tig > MVFu3QFxjGcYWkZiFtEpn4fpFLzhZVbmxzOzq/JTT33fH60ZJewCkUTVw3zfqBHE > bGyGiNhzZa4Se7cgtL4mkWEGyAmapfMwowM7SPqw3gew5G8lFZdpIKTe+4ECGEdH > dcHaXb28KghE8XUdcA02cWd0COhyFpdsJxuzqzKg3J8S/b4DMLMFcJRalBfTMcm3 > T9fSDxa5DwiEoJd0/HTF5ZBR4QQoAp9EOrNU+y2zjF9U7y5USA1smoXSBKQGtZTL > sCB3FFfrGoDHiVks4lhEDqGT+eFPK2cYZzi8RCG3sP8MhfNzaw7ZjUfwi2zjdu/D > scIAh8RexrAvuIG5svqTun7YppRFbTINSIB2Z3WVievJGCUa72ke5eC9cSAaW5Uv > MNoURhgp4lqXLNPiYyKMtJEgyQQrSQVT4Ty0MfxSEWwZVKrU6AQ2OGe/xCHiejSw > 0QqmDjrlA/4ntaimuw14 > =ahxh > -----END PGP SIGNATURE----- _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot
