On Tue, Jan 21, 2020 at 12:18:03AM +0100, Ard Biesheuvel wrote: > On Mon, 20 Jan 2020 at 23:31, Andy Shevchenko <andy.shevchenko@xxxxxxxxx> wrote: > > > > On Mon, Jan 20, 2020 at 9:28 PM Eric W. Biederman <ebiederm@xxxxxxxxxxxx> wrote: > > > Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx> writes: > > > > On Sat, Dec 17, 2016 at 06:57:21PM +0800, Dave Young wrote: > > > >> Ccing efi people. > > > >> > > > >> On 12/16/16 at 02:33pm, Jean Delvare wrote: > > > >> > On Fri, 16 Dec 2016 14:18:58 +0200, Andy Shevchenko wrote: > > > >> > > On Fri, 2016-12-16 at 10:32 +0800, Dave Young wrote: > > > >> > > > On 12/15/16 at 12:28pm, Jean Delvare wrote: > > > >> > > > > I am no kexec expert but this confuses me. Shouldn't the second > > > >> > > > > kernel have access to the EFI systab as the first kernel does? It > > > >> > > > > includes many more pointers than just ACPI and DMI tables, and it > > > >> > > > > would seem inconvenient to have to pass all these addresses > > > >> > > > > individually explicitly. > > > >> > > > > > > >> > > > Yes, in modern linux kernel, kexec has the support for EFI, I think it > > > >> > > > should work naturally at least in x86_64. > > > >> > > > > > >> > > Thanks for this good news! > > > >> > > > > > >> > > Unfortunately Intel Galileo is 32-bit platform. > > > >> > > > > >> > If it was done for X86_64 then maybe it can be generalized to X86? > > > >> > > > >> For X86_64, we have a new way for efi runtime memmory mapping, in i386 > > > >> code it still use old ioremap way. It is impossible to use same way as > > > >> the X86_64 since the virtual address space is limited. > > > >> > > > >> But maybe for 32bit, kexec kernel can run in physical mode, but I'm not > > > >> sure, I would suggest Andy to do a test first with efi=noruntime for > > > >> kexec 2nd kernel. > > > > > > > > Guys, it was quite a long no hear from you. As I told you the proposed work > > > > around didn't help. Today I found that Microsoft Surface 3 also affected > > > > by this. > > > > > > > > Can we apply these patches for now until you will find better > > > > solution? > > > > > > Not a chance. The patches don't apply to any kernel in the git history. > > > > > > Which may be part of your problem. You are or at least were running > > > with code that has not been merged upstream. > > > > It's done against linux-next. > > Applied clearly. (Not the version in this more than yearly old series > > of course, that's why I told I can resend) > > > > > > P.S. I may resend them rebased on recent vanilla. > > > > > > Second. I looked at your test results and they don't directly make > > > sense. dmidecode bypasses the kernel completely or it did last time > > > I looked so I don't know why you would be using that to test if > > > something in the kernel is working. > > > > > > However dmidecode failing suggests that the actual problem is something > > > in the first kernel is stomping the dmi tables. > > > > See below. > > > > > Adding a command line option won't fix stomped tables. > > > > It provides a mechanism, which seems to be absent, to the second > > kernel to know where to look for SMBIOS tables. > > > > > So what I would suggest is: > > > a) Verify that dmidecode works before kexec. > > > > Yes, it does. > > > > > b) Test to see if dmidecode works after kexec. > > > > No, it doesn't. > > > > > c) Once (a) shows that dmidecode works and (b) shows that dmidecode > > > fails figure out what is stomping your dmi tables during or before > > > kexec and that is what should get fixed. > > > > The problem here as I can see it that EFI and kexec protocols are not > > friendly to each other. > > I'm not an expert in either. That's why I'm asking for possible > > solutions. And this needs to be done in kernel to allow drivers to > > work. > > > > Does the > > > > commit 4996c02306a25def1d352ec8e8f48895bbc7dea9 > > Author: Takao Indoh <indou.takao@xxxxxxxxxxxxxx> > > Date: Thu Jul 14 18:05:21 2011 -0400 > > > > ACPI: introduce "acpi_rsdp=" parameter for kdump > > > > description shed a light on this? > > > > > Now using a non-efi method of dmi detection relies on the > > > tables being between 0xF0000 and 0x10000. AKA the last 64K > > > of the first 1MiB of memory. You might check to see if your > > > dmi tables are in that address range. > > > > # dmidecode --no-sysfs > > # dmidecode 3.2 > > Scanning /dev/mem for entry point. > > # No SMBIOS nor DMI entry point found, sorry. > > > > === with patch applied === > > # dmidecode > > ... > > Release Date: 03/10/2015 > > ... > > > > > > > > Otherwise I suspect the good solution is to give efi it's own page > > > tables in the kernel and switch to it whenever efi functions are called. > > > > > > > > But on 32bit the Linux kernel has historically been just fine directly > > > accessing the hardware, and ignoring efi and all of the other BIOS's. > > > > It seems not only for 32-bit Linux kernel anymore. MS Surface 3 runs > > 64-bit code. > > > > > So if that doesn't work on Intel Galileo that is probably a firmware > > > problem. > > > > It's not only about Galileo anymore. > > > > Looking at the x86 kexec EFI code, it seems that it has special > handling for the legacy SMBIOS table address, but not for the SMBIOS3 > table address, which was introduced to accommodate SMBIOS tables > living in memory that is not 32-bit addressable. > > Could anyone check whether these systems provide SMBIOS 3.0 tables, > and whether their address gets virtually remapped at ExitBootServices? Can you tell how to do this and I will try to get information? -- With Best Regards, Andy Shevchenko
