Re: [Qemu-devel] [PATCH] target-xtensa: fix missing errno codes for mingw32

[Max Filippov]

On Sat, Sep 8, 2012 at 12:22 AM, Stefan Weil <address@hidden> wrote:
> Am 06.09.2012 14:48, schrieb Max Filippov:
>
>> On Thu, Sep 6, 2012 at 8:45 AM, Stefan Weil<address@hidden>  wrote:
>>>
>>> Am 06.09.2012 02:36, schrieb Max Filippov:
>>>
>>>> Put the following errno value mappings under #ifdef:
>>>>
>>>> xtensa-semi.c: In function 'errno_h2g':
>>>> xtensa-semi.c:113: error: 'ENOTBLK' undeclared (first use in this
>>>> function)
>>>> xtensa-semi.c:113: error: (Each undeclared identifier is reported only
>>>> once
>>>> xtensa-semi.c:113: error: for each function it appears in.)
>>>> xtensa-semi.c:113: error: array index in initializer not of integer type
>>>> xtensa-semi.c:113: error: (near initialization for 'guest_errno')
>>>> xtensa-semi.c:124: error: 'ETXTBSY' undeclared (first use in this
>>>> function)
>>>> xtensa-semi.c:124: error: array index in initializer not of integer type
>>>> xtensa-semi.c:124: error: (near initialization for 'guest_errno')
>>>> xtensa-semi.c:134: error: 'ELOOP' undeclared (first use in this
>>>> function)
>>>> xtensa-semi.c:134: error: array index in initializer not of integer type
>>>> xtensa-semi.c:134: error: (near initialization for 'guest_errno')
>>>>
>>>> Signed-off-by: Max Filippov<address@hidden>
>>>> ---
>>>>
>>>
>>> Is semi hosting a useful feature when QEMU runs on a Windows host?
>>
>>
>> It should be if windows is POSIX enough.
>>
>>> If not, you could conditionally compile the whole semi hosting code
>>> for non Windows only.
>>>
>>> If yes, what about the differences in system calls between UNIX like
>>> operating systems and Windows? Should the code for 'open' add O_BINARY?
>>
>>
>> ...otherwise \n will turn to \r\n? IIRC this behaviour was tunable at the
>> system
>> level under cygwin. Not under mingw?
>>
>> Is there a list of such differences?
>
> Signed-off-by: Stefan Weil <address@hidden>
>
> Blue, please take the patch as it is and commit it:
> compilation for MinGW is currently broken, and the patch fixes that.
>
> The system calls should be handled by a separate patch.
>
> Yes, 'open' with MinGW opens files in text mode by default.
> That implies automatic translation from \n to \r\n on writes
> and vice versa on read. It also implies that seeking can give
> unexpected results.

Looks like open flags need mapping for bits other than
O_RD/WR/RDWR, I'll post a patch.

> Or-ing the flags for open with O_BINARY would fix the problem
> and works also for other OS were we define O_BINARY = 0.
>
> Like Cygwin, MinGW also supports linking with binmode.o.
> That file changes the default for open to binary mode,
> so all open calls in QEMU would automatically be binary.
>
> Maybe that second alternative is the better one.
>
> I noticed that lseek takes an int32_t offset. Is this
> intentional? It limits file size to 2 GiB.

Yes, unfortunately offset is passed in single 32-bit register.

> I did not see other potential problems with the system calls.

Thanks for the review, Stefan.

-- 
Thanks.
-- Max