On Tue, 21 May 2024 at 17:42, Jiaxun Yang <jiaxun.y...@flygoat.com> wrote: > > > > 在2024年5月21日五月 下午2:58，Ilias Apalodimas写道： > > Hi Jiaxun, > > > > On Fri, 17 May 2024 at 19:33, Jiaxun Yang <jiaxun.y...@flygoat.com> wrote: > >> > >> Allow runtime relocate to be disabled because on MIPS we > >> never do that. It's guaranteed that OS won't call > >> set_virtual_address_map and convert_pointer as well. > > > > Who guarantees that? Is it only for Linux? > Hi Ilias, > > It's guarantee by all the existing implementations, ventoy, > linux etc. >
What's ventoy? Googling it seems to be a tool for writing images? > It's nearly impossible to run MIPS OS in virtual (or paged) > segment. All MIPS OS and bootloaders are running in KSEG/XKPHYS > segment, which directly mapping lower bits of virtual address > into physical address. So I suppose set_virtual_address_map > is unnecessary on MIPS because the mapping for U-Boot is > always here and can't be disabled in hardware. > Fair enough, I am not too happy with the restriction but I think it's ok to start with > > > >> > >> On MIPS KSEG0 is always mapped to memory and there is no > >> way to disable it for kernel mode. Both EFI runtime and > >> kernel lays in this segment, so relocation is totally > >> unnecessary. > >> > >> Also U-Boot does not use traditional .dyn.rel to perform > >> relocation on MIPS, that makes implementation of runtime > >> relocation pretty hard. > > > > It already works on other architectures so I suppose it's only a > > matter of adding it? > > MIPS is odd here, we are not compiling U-Boot with -fPIC, instead > we use our own tools to generate relocation records and embedded > them into U-Boot. > > Adding relocation support requires modifications to that tool > "tools/mips-relocs.c" and also processing our own record format > here. > > Given that set_virtual_address_map have no practice use on MIPS, > I think the best way to handle it is to leave set_virtual_address_map > alone. hrrm any idea why? Was that a pre-existing state in mips? Perhaps we can fix it in the future. That being said, I was away on a conference, I'll have a look at the mips patches, but probably next week Cheers /Ilias > > Thanks > > > > Thanks > > /Ilias > >> > [...] > -- > - Jiaxun
