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s390/cpcmd,vmcp: avoid GFP_DMA allocations

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According to the CP Programming Services manual Diagnose Code 8
"Virtual Console Function" can be used in all addressing modes. Also
the input and output buffers do not have a limitation which specifies
they need to be below the 2GB line.

This is true at least since z/VM 5.4.

Therefore remove the sam31/64 instructions and allow for simple
GFP_KERNEL allocations. This makes it easier to allocate a 1MB page
if the user requested such a large return buffer.

Signed-off-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
This commit is contained in:
Heiko Carstens
2017-08-07 15:16:15 +02:00
committed by Martin Schwidefsky
parent 267239cc10
commit cd4386a931
3 changed files with 8 additions and 14 deletions
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7
arch/s390/include/asm/cpcmd.h
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@@ -10,9 +10,8 @@
/*
* the lowlevel function for cpcmd
* the caller of __cpcmd has to ensure that the response buffer is below 2 GB
*/
extern int __cpcmd(const char *cmd, char *response, int rlen, int *response_code);
int __cpcmd(const char *cmd, char *response, int rlen, int *response_code);
/*
* cpcmd is the in-kernel interface for issuing CP commands
@@ -25,8 +24,8 @@ extern int __cpcmd(const char *cmd, char *response, int rlen, int *response_code
* response_code: return pointer for VM's error code
* return value: the size of the response. The caller can check if the buffer
* was large enough by comparing the return value and rlen
* NOTE: If the response buffer is not below 2 GB, cpcmd can sleep
* NOTE: If the response buffer is not in real storage, cpcmd can sleep
*/
extern int cpcmd(const char *cmd, char *response, int rlen, int *response_code);
int cpcmd(const char *cmd, char *response, int rlen, int *response_code);
#endif /* _ASM_S390_CPCMD_H */