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    SubjectRe: [PATCH v2 2/2] x86, kexec_file_load: make it work with efi=noruntime or efi=old_map
    + linux-acpi list
    On 01/17/19 at 03:49pm, Chao Fan wrote:
    > On Thu, Jan 17, 2019 at 03:41:13PM +0800, Kairui Song wrote:
    > >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.
    >
    > I think it's OK.
    > Try to read it, if get RSDP, use it.
    > If not, search in EFI/BIOS/... and refill the RSDP to
    > boot_params.acpi_rsdp_addr.
    > By the way, I search kernel code, I didn't find other code fill and
    > use it, only you(KEXEC) are trying to fill it.
    > If I miss something, please let me know.
    >
    > Thanks,
    > Chao Fan
    >
    > >
    > >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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