Hi Achin, On Wed, Jan 18, 2017 at 08:24:06PM +0000, [email protected] wrote: > From: Achin Gupta <[email protected]> > > The NOR flash banks were being mapped in the translation tables with the same > memory attributes as RAM in the system. These attributes mark the region as > Normal Memory and could additionally be cacheable or non-cacheable. > > Either type of attributes are unsuitable for NOR Flash since write operations > could be performed on it. Normal Memory does not guarantee ordering of > transactions that Device memory does. So the commands sent to the Flash device > may not arrive in the right order unless barriers are used. Commands might not > get past the CPU caches in case the region has been mapped with cacheable > attributes. > > This patch fixes the problem by mapping the NOR Flash memory region with > Device > memory attributes.
To add some background to Ard's comment - this was not unintentionally done: https://github.com/tianocore/edk2/commit/19bb46c411279dcd30d540c56e5993c5f771c319 Was the reasoning behind this commit incorrect - do you have a (pre-DXE?) use-case that creates a problem? Regards, Leif > Contributed-under: TianoCore Contribution Agreement 1.0 > Signed-off-by: Achin Gupta <[email protected]> > --- > ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git > a/ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c > b/ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c > index 14c7e8e..2685114 100644 > --- a/ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c > +++ b/ArmPlatformPkg/ArmVExpressPkg/Library/ArmVExpressLibRTSM/RTSMMem.c > @@ -116,7 +116,7 @@ ArmPlatformGetVirtualMemoryMap ( > VirtualMemoryTable[++Index].PhysicalBase = ARM_VE_SMB_NOR0_BASE; > VirtualMemoryTable[Index].VirtualBase = ARM_VE_SMB_NOR0_BASE; > VirtualMemoryTable[Index].Length = ARM_VE_SMB_NOR0_SZ + ARM_VE_SMB_NOR1_SZ; > - VirtualMemoryTable[Index].Attributes = CacheAttributes; > + VirtualMemoryTable[Index].Attributes = ARM_MEMORY_REGION_ATTRIBUTE_DEVICE; > > // SMB CS2 - SRAM > VirtualMemoryTable[++Index].PhysicalBase = ARM_VE_SMB_SRAM_BASE; > -- > 1.9.1 > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
