Hi Alex, On 26 August 2018 at 19:11, Alexander Graf <ag...@suse.de> wrote: > > > On 08.08.18 11:54, Simon Glass wrote: >> At present map_sysmem() maps an address into the sandbox RAM buffer, >> return a pointer, while map_to_sysmem() goes the other way. >> >> The mapping is currently just 1:1 since a case was not found where a more >> flexible mapping was needed. PCI does have a separate and more complex >> mapping, but uses its own mechanism. >> >> However this arrange cannot handle one important case, which is where a >> test declares a stack variable and passes a pointer to it into a U-Boot >> function which uses map_to_sysmem() to turn it into a address. Since the >> pointer is not inside emulated DRAM, this will fail. >> >> Add a mapping feature which can handle any such pointer, mapping it to a >> simple tag value which can be passed around in U-Boot as an address. >> >> Signed-off-by: Simon Glass <s...@chromium.org> > > I think you are aware that this logic will fall apart spectacularly if > any arithmetic operation happens on the virtual (U-Boot) address, right? > So simple code like > > readl(vaddr + 1); > > will just fail (hopefully) or (more likely) return a completely > incorrect value. > > I assume this is intentional, but shouldn't the tag increment be > something slightly larger then?
What do you expect readl() to do on sandbox? At present it is just a no-op. I suppose we could support memory-mapped I/O but it has not been attempted yet. Regards, Simon _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de https://lists.denx.de/listinfo/u-boot
