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SubjectRe: [PATCH v2 2/2] x86, kexec_file_load: make it work with efi=noruntime or efi=old_map
On Wed, Jan 16, 2019 at 5:46 PM Borislav Petkov <bp@alien8.de> wrote:
>
> On Wed, Jan 16, 2019 at 03:08:42PM +0800, Kairui Song wrote:
> > I didn't see a way to reuse things in that patch series, situation is
> > different, in that patch it needs to get RSDP in very early boot stage
> > so it did everything from scratch, in this patch kexec_file_load need
> > to get RSDP too, but everything is well setup so things are a lot
> > easier, just read from current boot_prams, efi and fallback to
> > acpi_find_root_pointer should be good.
>
> No no. Early code should find out that venerable RSDP thing once and
> will save it somewhere for further use. No gazillion parsings of it.
> Just once and share it with the rest of the code that needs it.
>

How about we refill the boot_params.acpi_rsdp_addr if it is not valid
in early code, so it could be used as a reliable RSDP address source?
That should make things easier.

But if early code should parse it and store it should be done in
Chao's patch, or I can post another patch to do it if Chao's patch is
merged.

For now I think good to have something like this in this patch series
to always keep storing acpi_rsdp in late code,
acpi_os_get_root_pointer_late (maybe comeup with a better name later)
could be used anytime to get RSDP and no extra parsing:

--- a/drivers/acpi/osl.c
+++ b/drivers/acpi/osl.c
@@ -180,8 +180,8 @@ void acpi_os_vprintf(const char *fmt, va_list args)
#endif
}

-#ifdef CONFIG_KEXEC
static unsigned long acpi_rsdp;
+#ifdef CONFIG_KEXEC
static int __init setup_acpi_rsdp(char *arg)
{
return kstrtoul(arg, 16, &acpi_rsdp);
@@ -189,28 +189,38 @@ static int __init setup_acpi_rsdp(char *arg)
early_param("acpi_rsdp", setup_acpi_rsdp);
#endif

+acpi_physical_address acpi_os_get_root_pointer_late(void) {
+ return acpi_rsdp;
+}
+
acpi_physical_address __init acpi_os_get_root_pointer(void)
{
acpi_physical_address pa;

-#ifdef CONFIG_KEXEC
if (acpi_rsdp)
return acpi_rsdp;
-#endif
+
pa = acpi_arch_get_root_pointer();
- if (pa)
+ if (pa) {
+ acpi_rsdp = pa;
return pa;
+ }

if (efi_enabled(EFI_CONFIG_TABLES)) {
- if (efi.acpi20 != EFI_INVALID_TABLE_ADDR)
+ if (efi.acpi20 != EFI_INVALID_TABLE_ADDR) {
+ acpi_rsdp = efi.acpi20;
return efi.acpi20;
- if (efi.acpi != EFI_INVALID_TABLE_ADDR)
+ }
+ if (efi.acpi != EFI_INVALID_TABLE_ADDR) {
+ acpi_rsdp = efi.acpi;
return efi.acpi;
+ }
pr_err(PREFIX "System description tables not found\n");
} else if (IS_ENABLED(CONFIG_ACPI_LEGACY_TABLES_LOOKUP)) {
acpi_find_root_pointer(&pa);
}

+ acpi_rsdp = pa;
return pa;
}
> --
> Regards/Gruss,
> Boris.
>
> Good mailing practices for 400: avoid top-posting and trim the reply.
--
Best Regards,
Kairui Song

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