Re: [XEN PATCH v4 18/18] build, include: rework compat-build-header.py

[Anthony PERARD <anthony.perard@xxxxxxxxxx>]

On Wed, Apr 08, 2020 at 03:56:02PM +0200, Jan Beulich wrote:
> On 31.03.2020 12:31, Anthony PERARD wrote:
> > Replace a mix of shell script and python script by all python script.
> > 
> > Remove the unnecessary "grep -v '^# [0-9]'". It is to hide the
> > linemarkers generated by the preprocessor. But adding -P inhibit there
> > generation, thus the grep isn't needed anymore.
> > 
> > gcc -E -P and clang -E -P have different behavior. While both don't
> > generates linemarkers, gcc also removes all empty lines while clang
> > keep them all. We don't need those empty lines, so we don't generates
> > them in the final compat/%.h headers. (This replace `uniq` which was
> > only de-duplicating empty line.)
> > 
> > The only changes in the final generated headers it that they don't
> > have empty lines anymore.
> 
> Making them harder to read? While typically no-one needs to look at
> their contents, in case of problems it helps if generated files are
> half way accessible to a human as well.

I do think they are still readable. Those empty lines don't add much.
There are so many of them that a `uniq` is needed...

For example, with dm_op.h, we have this:

<<<<<<< before
#pragma pack(4)
typedef uint16_t ioservid_compat_t;
struct compat_dm_op_create_ioreq_server {

    uint8_t handle_bufioreq;
    uint8_t pad[3];

    ioservid_compat_t id;
};
struct compat_dm_op_get_ioreq_server_info {

    ioservid_compat_t id;

    uint16_t flags;

    evtchn_port_compat_t bufioreq_port;

    uint64_t ioreq_gfn;

    uint64_t bufioreq_gfn;
};
struct compat_dm_op_ioreq_server_range {

    ioservid_compat_t id;
    uint16_t pad;

    uint32_t type;

    uint64_t start, end;
};
=======
#pragma pack(4)
typedef uint16_t ioservid_compat_t;
struct compat_dm_op_create_ioreq_server {
    uint8_t handle_bufioreq;
    uint8_t pad[3];
    ioservid_compat_t id;
};
struct compat_dm_op_get_ioreq_server_info {
    ioservid_compat_t id;
    uint16_t flags;
    evtchn_port_compat_t bufioreq_port;
    uint64_t ioreq_gfn;
    uint64_t bufioreq_gfn;
};
struct compat_dm_op_ioreq_server_range {
    ioservid_compat_t id;
    uint16_t pad;
    uint32_t type;
    uint64_t start, end;
};
>>>>>>> after

Thanks,

-- 
Anthony PERARD