Implement standard file operation with QEMU

casmac Wed, 15 Jul 2020 17:53:49 -0700

Hi all,
&nbsp; I am trying to implment standard file operation (stdio) with QEMU for 
DSP architecture. The manufacture (TI) provides a runtime library that support 
posix standard IO, but it left the device level implmentation as hook function 
calls, like  in the library source , it contains&nbsp; add_device() function, 
and write(),read(),open() are not implemented:




int add_device(char&nbsp;&nbsp;&nbsp; &nbsp; *name,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
unsigned &nbsp; flags,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*dopen)&nbsp; (const char *path, unsigned flags, 
int foo),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*dclose) (int fno),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*dread)&nbsp; (int fno, char *buf, unsigned 
count),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*dwrite) (int fno, const char *buf, unsigned 
count),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
fpos_t&nbsp;&nbsp; &nbsp; (*dlseek) (int fno, fpos_t offset, int origin),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*dunlink)(const char *path),
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; 
int&nbsp;&nbsp;&nbsp; &nbsp; (*drename)(const char *old_name, const char 
*new_name))
{
&nbsp;&nbsp; _DEVICE *dt;

&nbsp;&nbsp; strncpy(dt-&gt;name,name,8);
&nbsp;&nbsp; dt-&gt;name[8] = '\0';
&nbsp;&nbsp; dt-&gt;flags &nbsp; = flags;
&nbsp;&nbsp; dt-&gt;OPEN&nbsp; &nbsp; = dopen;
&nbsp;&nbsp; dt-&gt;CLOSE &nbsp; = dclose;
&nbsp;&nbsp; dt-&gt;READ&nbsp; &nbsp; = dread;
&nbsp;&nbsp; dt-&gt;WRITE &nbsp; = dwrite;
&nbsp;&nbsp; dt-&gt;LSEEK &nbsp; = dlseek;
&nbsp;&nbsp; dt-&gt;UNLINK&nbsp; = dunlink;
&nbsp;&nbsp; dt-&gt;RENAME&nbsp; = drename;
}


int write(int&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; fildes,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; const char &nbsp; *bufptr,
&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; &nbsp; unsigned&nbsp;&nbsp;&nbsp; 
&nbsp; cnt)
{
&nbsp;&nbsp; 
/*------------------------------------------------------------------------*/
&nbsp;&nbsp; /* CALL FUNCTION FROM DEVICE TABLE TO PERFORM WRITE FOR THIS 
DEVICE/FILE&nbsp; */
&nbsp;&nbsp; 
/*------------------------------------------------------------------------*/
&nbsp;&nbsp; return (*(_stream[fildes]-&gt;WRITE)) (fildes,bufptr,cnt);
}



&nbsp;&nbsp; Then, how can we use this runtime library together with QEMu to 
implement full-stack file oerations?&nbsp; I  really appreaciate any advice.


&nbsp; Thanks.
regards,
xiaolei

Implement standard file operation with QEMU

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