From: Masayoshi Mizuma <[email protected]>
kexec reboot sometime fails in early boot sequence on aarch64 machine.
That is because kexec overwrites the LPI property tables and pending
tables with the initrd.
To avoid the overwrite, introduce /proc/efi/memreserve to tell the
tables region to kexec so that kexec can avoid the memory region to
locate initrd.
kexec also needs a patch to handle /proc/efi/memreserve. I'm preparing
the patch for kexec.
Changelog
v2: - Change memreserve file location from sysfs to procfs.
memreserve may exceed the PAGE_SIZE in case efi_memreserve_root
has a lot of entries. So we cannot use sysfs_kf_seq_show().
Use seq_printf() in procfs instead.
Masayoshi Mizuma (2):
efi: add /proc/efi directory
efi: arm64: Introduce /proc/efi/memreserve to tell the persistent
pages
drivers/firmware/efi/efi.c | 93 +++++++++++++++++++++++++++++++++++++-
1 file changed, 92 insertions(+), 1 deletion(-)
--
2.18.1
From: Masayoshi Mizuma <[email protected]>
Add /proc/efi directory to show some efi internal information.
Signed-off-by: Masayoshi Mizuma <[email protected]>
---
drivers/firmware/efi/efi.c | 22 ++++++++++++++++++++++
1 file changed, 22 insertions(+)
diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index d101f072c..d8157cb34 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -325,6 +325,22 @@ static __init int efivar_ssdt_load(void)
static inline int efivar_ssdt_load(void) { return 0; }
#endif
+#ifdef CONFIG_PROC_FS
+static struct proc_dir_entry *proc_efi;
+static int __init efi_proc_init(void)
+{
+ proc_efi = proc_mkdir("efi", NULL);
+ if (!proc_efi) {
+ pr_err("/proc/efi: Cannot create /proc/efi directory.\n");
+ return 1;
+ }
+
+ return 0;
+}
+#else
+static inline int efi_proc_init(void) { return 0; }
+#endif /* CONFIG_PROC_FS */
+
/*
* We register the efi subsystem with the firmware subsystem and the
* efivars subsystem with the efi subsystem, if the system was booted with
@@ -381,6 +397,12 @@ static int __init efisubsys_init(void)
goto err_remove_group;
}
+ error = efi_proc_init();
+ if (error) {
+ sysfs_remove_mount_point(efi_kobj, "efivars");
+ goto err_remove_group;
+ }
+
return 0;
err_remove_group:
--
2.18.1
On Tue, 3 Dec 2019 at 20:14, Masayoshi Mizuma <[email protected]> wrote:
>
> From: Masayoshi Mizuma <[email protected]>
>
> kexec reboot sometime fails in early boot sequence on aarch64 machine.
> That is because kexec overwrites the LPI property tables and pending
> tables with the initrd.
>
> To avoid the overwrite, introduce /proc/efi/memreserve to tell the
> tables region to kexec so that kexec can avoid the memory region to
> locate initrd.
>
> kexec also needs a patch to handle /proc/efi/memreserve. I'm preparing
> the patch for kexec.
>
> Changelog
> v2: - Change memreserve file location from sysfs to procfs.
> memreserve may exceed the PAGE_SIZE in case efi_memreserve_root
> has a lot of entries. So we cannot use sysfs_kf_seq_show().
> Use seq_printf() in procfs instead.
>
> Masayoshi Mizuma (2):
> efi: add /proc/efi directory
> efi: arm64: Introduce /proc/efi/memreserve to tell the persistent
> pages
>
Apologies for the tardy response.
Adding /proc/efi is really out of the question. *If* we add any
special files to expose this information, it should be under sysfs.
However, this is still only a partial solution, since it only solves
the problem for userspace based kexec, and we need something for
kexec_file_load() as well.
The fundamental issue here is that /proc/iomem apparently lacks the
entries that describe these regions as 'reserved', so we should try to
address that instead.