diff options
Diffstat (limited to 'Documentation/powerpc/cxlflash.txt')
| -rw-r--r-- | Documentation/powerpc/cxlflash.txt | 42 |
1 files changed, 38 insertions, 4 deletions
diff --git a/Documentation/powerpc/cxlflash.txt b/Documentation/powerpc/cxlflash.txt index 4202d1bc583c..f4c119092b98 100644 --- a/Documentation/powerpc/cxlflash.txt +++ b/Documentation/powerpc/cxlflash.txt @@ -171,11 +171,30 @@ DK_CXLFLASH_ATTACH destroyed, the tokens are to be considered stale and subsequent usage will result in errors. + - A valid adapter file descriptor (fd2 >= 0) is only returned on + the initial attach for a context. Subsequent attaches to an + existing context (DK_CXLFLASH_ATTACH_REUSE_CONTEXT flag present) + do not provide the adapter file descriptor as it was previously + made known to the application. + - When a context is no longer needed, the user shall detach from - the context via the DK_CXLFLASH_DETACH ioctl. + the context via the DK_CXLFLASH_DETACH ioctl. When this ioctl + returns with a valid adapter file descriptor and the return flag + DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_ + close the adapter file descriptor following a successful detach. + + - When this ioctl returns with a valid fd2 and the return flag + DK_CXLFLASH_APP_CLOSE_ADAP_FD is present, the application _must_ + close fd2 in the following circumstances: + + + Following a successful detach of the last user of the context + + Following a successful recovery on the context's original fd2 + + In the child process of a fork(), following a clone ioctl, + on the fd2 associated with the source context - - A close on fd2 will invalidate the tokens. This operation is not - required by the user. + - At any time, a close on fd2 will invalidate the tokens. Applications + should exercise caution to only close fd2 when appropriate (outlined + in the previous bullet) to avoid premature loss of I/O. DK_CXLFLASH_USER_DIRECT ----------------------- @@ -254,6 +273,10 @@ DK_CXLFLASH_DETACH success, all "tokens" which had been provided to the user from the DK_CXLFLASH_ATTACH onward are no longer valid. + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ close the fd2 associated with the context + following the detach of the final user of the context. + DK_CXLFLASH_VLUN_CLONE ---------------------- This ioctl is responsible for cloning a previously created @@ -261,7 +284,7 @@ DK_CXLFLASH_VLUN_CLONE support maintaining user space access to storage after a process forks. Upon success, the child process (which invoked the ioctl) will have access to the same LUNs via the same resource handle(s) - and fd2 as the parent, but under a different context. + as the parent, but under a different context. Context sharing across processes is not supported with CXL and therefore each fork must be met with establishing a new context @@ -275,6 +298,12 @@ DK_CXLFLASH_VLUN_CLONE translation tables are copied from the parent context to the child's and then synced with the AFU. + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ close the fd2 associated with the source + context (still resident/accessible in the parent process) following the + clone. This is to avoid a stale entry in the file descriptor table of the + child process. + DK_CXLFLASH_VERIFY ------------------ This ioctl is used to detect various changes such as the capacity of @@ -309,6 +338,11 @@ DK_CXLFLASH_RECOVER_AFU at which time the context/resources they held will be freed as part of the release fop. + When the DK_CXLFLASH_APP_CLOSE_ADAP_FD flag was returned on a successful + attach, the application _must_ unmap and close the fd2 associated with the + original context following this ioctl returning success and indicating that + the context was recovered (DK_CXLFLASH_RECOVER_AFU_CONTEXT_RESET). + DK_CXLFLASH_MANAGE_LUN ---------------------- This ioctl is used to switch a LUN from a mode where it is available |