Re: [Crash-utility] What is the current state of the 5-level page tables in Crash

Hi Dave, At 12/20/2017 02:15 AM, Dave Anderson wrote: > > > ----- Original Message ----- >> Dear Dave, >> >> I saw your commit >> >> 307e7f35f510("First phase of future support for x86_64 5-level page >> tables.") >> >> in crash git-tree. It is the preparatory for x86_64 5-level page tables. >> There may be more things to be done to support for 5-level. > > Right. There needs to be a manner of determining very early on whether > the kernel page tables are using 5-level. And during crash runtime, there > needs to be a manner of determining whether each user-space task is using > 4- or 5-level page tables. Also, it may be possible/preferable to > squeeze the 5-level support into the currently existing x86_64_kvtop() and > x86_64_uvtop() functions instead of using the new xxx_5level() function > placeholders that I added in the preparatory patch. > It is really helpful to me. >> >> I hope to know: >> >> 1. What is the current state of the 5-level page table in Crash? > > I have done nothing further beyond than the preparatory steps in that > commit. > >> >> 2. If there are some reason that we should pause the support work of >> 5-level page tables currently. > > No, not really. I originally delayed further work because originally it > was enabled by kernel CONFIG, but as I understand it now, it is enabled by > a combination of a kernel CONFIG and a boot command line option? But I am sorry I just found the CONFIG_X86_5LEVEL, Could you tell me the name of boot command line option?

> since I have never seen or worked with a kernel with it enabled, I've Indeed, we only can use it in QEmu now. > not done anything further. Yes, I see. > >> >> 3. Are you already doing it? > > No. Are you offering to complete the work? > Aha, I am willing to, But I am not familiar with crash, I will try me best to do it. Thanks, dou