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00c2cae6b6
clang points out that the lpfc_name structure has an 8-byte alignment
requirement on most architectures, but is embedded in a number of other
structures that are forced to be only 1-byte aligned:
drivers/scsi/lpfc/lpfc_hw.h:1516:30: error: field pe within 'struct lpfc_fdmi_reg_port_list' is less aligned than 'struct lpfc_fdmi_port_entry' and is usually due to 'struct lpfc_fdmi_reg_port_list' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
struct lpfc_fdmi_port_entry pe;
drivers/scsi/lpfc/lpfc_hw.h:850:19: error: field portName within 'struct _ADISC' is less aligned than 'struct lpfc_name' and is usually due to 'struct _ADISC' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
drivers/scsi/lpfc/lpfc_hw.h:851:19: error: field nodeName within 'struct _ADISC' is less aligned than 'struct lpfc_name' and is usually due to 'struct _ADISC' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
drivers/scsi/lpfc/lpfc_hw.h:922:19: error: field portName within 'struct _RNID' is less aligned than 'struct lpfc_name' and is usually due to 'struct _RNID' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
drivers/scsi/lpfc/lpfc_hw.h:923:19: error: field nodeName within 'struct _RNID' is less aligned than 'struct lpfc_name' and is usually due to 'struct _RNID' being packed, which can lead to unaligned accesses [-Werror,-Wunaligned-access]
From the git history, I can see that all the __packed annotations were done
specifically to avoid introducing implicit padding around the lpfc_name
instances, though this was probably the wrong approach.
To improve this, only annotate the one uint64_t field inside of lpfc_name
as packed, with an explicit 4-byte alignment, as is the default already on
the 32-bit x86 ABI but not on most others. With this, the other __packed
annotations can be removed again, as this avoids the incorrect padding.
Two other structures change their layout as a result of this change:
- struct _LOGO never gained a __packed annotation even though it has the
same alignment problem as the others but is not used anywhere in the
driver today.
- struct serv_param similarly has this issue, and it is used, my guess is
that this is only an internal structure rather than part of a binary
interface, so the padding has no negative effect here.
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Link: https://lore.kernel.org/r/20230616090705.2623408-1-arnd@kernel.org
Reviewed-by: Justin Tee <justin.tee@broadcom.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
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Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
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https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.
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requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.