On 9/11/19 8:16 AM, AKASHI Takahiro wrote:
Heinrich,
On Fri, Aug 23, 2019 at 09:04:21AM +0900, AKASHI Takahiro wrote:
On Thu, Aug 22, 2019 at 12:52:41PM +0200, Heinrich Schuchardt wrote:
On 8/22/19 11:11 AM, Mark Kettenis wrote:
From: AKASHI Takahiro <takahiro.aka...@linaro.org>
Date: Thu, 22 Aug 2019 17:06:25 +0900
Currently, a whole disk without any partitions is not associated
with EFI_SIMPLE_FILE_SYSTEM_PROTOCOL. So even if it houses FAT
file system, there is a chance that we may not be able to access
it, particularly, when accesses are to be attempted after searching
that protocol against a device handle.
With this patch, EFI_SIMPLE_FILE_SYSTEM_PROTOCOL is installed
to such a disk if part_get_info() shows there is not partition
table installed on it.
Do other UEFI implementations support this?
What use cases exist that come without partition table?
I didn't find any *explicit* description in UEFI specification
that mandates that any block device should have a partition table.
It may be mandatory for boot(able) disks, but for others?
You can create an MBR with partition table that is a valid start of a
file system.
Obviously we can do that, but if this is not a mandatory requirement,
we'd better support no-partitioned cases.
I did not mean this as a requirement but as a source of errors.
My idea is that could have an MBR which by chance looks like the start
of a file system. When you now expose this non-existent file system the
UEFI client may create havoc.
Any further comments?
-Takahiro Akashi
So you should first check if a partition table exists. Only if none
exists you can test for a possible file system.
I don't get your point. Are you saying that we should support a file system
for a disk only if it has a file system?
This is not true even for existing partitions as FILE_SYSTEM PROTOCOL
is always installed to every partition whether or not it really
houses a file system under the current implementation.
That sounds like a bug. If a partition isn't formatted we would not even
know whether to call the FAT or the EXT4 driver.
Regards
Heinrich
Thanks,
-Takahiro Akashi
Best regards
Heinrich
Signed-off-by: AKASHI Takahiro <takahiro.aka...@linaro.org>
---
lib/efi_loader/efi_disk.c | 4 +++-
1 file changed, 3 insertions(+), 1 deletion(-)
diff --git a/lib/efi_loader/efi_disk.c b/lib/efi_loader/efi_disk.c
index 7a6b06821a47..548fe667e6f8 100644
--- a/lib/efi_loader/efi_disk.c
+++ b/lib/efi_loader/efi_disk.c
@@ -239,6 +239,7 @@ static efi_status_t efi_disk_add_dev(
struct efi_disk_obj **disk)
{
struct efi_disk_obj *diskobj;
+ disk_partition_t info;
efi_status_t ret;
/* Don't add empty devices */
@@ -270,7 +271,8 @@ static efi_status_t efi_disk_add_dev(
diskobj->dp);
if (ret != EFI_SUCCESS)
return ret;
- if (part >= 1) {
+ /* partitions or whole disk without partitions */
+ if (part >= 1 || part_get_info(desc, part, &info)) {
diskobj->volume = efi_simple_file_system(desc, part,
diskobj->dp);
ret = efi_add_protocol(&diskobj->header,
--
2.21.0
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