JPS63124150A - Address converting system - Google Patents

Abstract

PURPOSE:To ensure the fine control for sharing a virtual address space with no conflict by providing a type field containing plural flags, an address field and a protection field. CONSTITUTION:A type field (Type) consists of a flag RA showing whether the restorage is needed or not, a flag US which designates a space in a restorage mode, and a flag PM which designates use or non-use of the protection information on a restoring destination. While an address field (Addr) includes a logical or physical address in response to the flag RA. Then a protection field (Prot) includes the protection information on read R, write W and execution E. Then it is decided based on the Type whether the restoration is carried out or not after a descriptor is read. If so, the Addr is defined as a logical address to perform conversion of address again. If not, the Addr is defined as a physical address and put into the access of a main memory. Thus a virtual address space can be finely shared and furthermore controlled with no conflict.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an address translation method, and particularly to an address translation method suitable for sharing a portion of a virtual address space.

[Conventional technology]

As a method of sharing a part of the virtual address space, as described in JP-A-49-73338, the logical address is separated into a user space and a system space, and the system space can be commonly accessed by multiple user spaces. There is a way to do this. Generally speaking, this method is from the top 1 of logical addresses to
Using about 2 bits, for example, the larger address is used as system space.

A method is adopted in which the smaller one is used as the user space. Although this method is easy to understand and highly practical, it is not suitable for fine-grained control, such as when you want to share data only between specific users, or when you want to share only some data within a certain address range.

On the other hand, as another method, there is a method in which multiple descriptors specify the same physical address. Although this is a commonly used method, extreme care must be taken when performing memory management using the so-called demand paging method, in which data in main memory is transferred to and returned from a file. This is because the state of the main memory is often managed by the descriptor of the conversion table, so the management part is distributed, and the state of the main memory must be reflected on multiple descriptors at the same time.

[Problem that the invention seeks to solve]

As described above, in the conventional technology, it is difficult to perform fine-grained control such as sharing some data among some users. Furthermore, in order to realize such a sharing method, it is necessary to pay sufficient attention to the sharing status of multiple descriptors and manage them.

SUMMARY OF THE INVENTION An object of the present invention is to provide an address translation method that solves the above-mentioned problems and manages sharing of a virtual address space in detail and without contradiction.

[Means for solving the problem] The above purpose is to have a flag or code in the descriptor of the address translation table that indicates that the translation table is to be redrawn, and if necessary, a conversion table or logic used for further redrawing. This can be achieved by having a means to specify an address.

[Effect]

Each descriptor in the translation table has a flag indicating whether or not to perform redirection. If the flag requests redirection, address conversion is executed using the virtual address space and logical address to be redirected. As a result, the redirection source address can share the same memory area as the redirection destination address. Furthermore, since the unit of sharing is the range specified by the descriptor, sharing can be controlled in detail, and since the redrawing source descriptor does not contain information regarding main memory management, no management conflicts occur.

〔Example〕

The present invention will be explained in detail below.

FIG. 1 shows an example of segment sharing in virtual space. FIG. 1(a) shows the space St and the space S2 and the sharing relationship of segments between them. The vertical direction of each space is the direction of the logical address. In this example, the data is divided into eight segments using an address translation table. Segments 2 and 3 of space S1 are shared by segments (2) and (3) of space S2 using different space addresses.

Furthermore, segment 5 of space S1 is shared by segment (5) in the same space S1 at the same space-separate address. Furthermore, segment 7 of space Sz is segment (
7), the same address is shared in a separate space. There are various ways of sharing in this way. The same figure (b
) shows the relationship between the conversion table, main memory, and files in such a spatial structure. Conversion table T1. T
Descriptors 1-12 of z specify addresses in main memory M or indicate that the contents are on file F. On the other hand, descriptor a=d that specifies redrawing
specifies the translation table and logical address to be used for redirection. 1iijl(c) is an example of a descriptor. ■ indicates whether the descriptor is valid or invalid,
Type indicates the type of descriptor. For example, 0'' is a normal descriptor, and the next Addr specifies a physical address.

Further, "1" indicates redrawing, and Ac1dr specifies the logical address for redrawing. Alternatively, it is also possible to specify the type of redrawing here. For example, same address in different space,
These include addresses for different spaces, addresses for different spaces, and the like.

Prof indicates access protection conditions. ~ indicates that other information may be added.

Figure 2 shows system space SS and user space USI.

In a system having US2 and in which the user space is multiplexed, a method is shown in which the system space can access the user space.

In this case, system space and user space are distinguished, for example, by a privileged mode flag within the processor.

Therefore, if you want to read the user space in privileged mode, use the conversion table SST for system space.
For the descriptor whose user space is to be accessed, the type field TF is set to 1''.In this case, it is assumed that the accessed logical address is used to specify that redirection be performed in the user space.

Then, even if the user space is switched from user 1 to user 2 to another user space, the user space assigned at that time can be accessed.

FIG. 3 shows a case where data is shared between specific users. (a) shows the structure of space. It is assumed that user shared spaces C1 and 02 are allocated in the system space and can be accessed by logical addresses A and B, respectively. On the other hand, it is assumed that users 1 and 2 share C1 and 02, and user 3 shares only C1.

Further, the logical address for the same shared area differs for each user. Such a case can be realized by the table shown in (b). That is, by setting the type field in the user table to, for example, l#2jj, the redrawing of the system space is indicated. Also, the address field at that time is A, which is a logical address on the system space.
Or put B in it.

FIG. 4(a) is an example of a descriptor for implementing the present invention. The type field (Type) consists of a flag RA indicating whether redrawing is to be performed, a flag US specifying the space at the time of redrawing, and a flag PM specifying whether or not to use the protection information of the redrawing destination. address field (
Addr) contains either a logical address or a physical address depending on the RA flag.

The protected field (Pvot) can be read (R) and written (
W), protection conditions regarding execution (E) are entered. Same figure (b)
shows the relationship between the value of the type field and the function F of the descriptor. Here, in the protection section, a circle mark indicates "valid" and an x mark indicates "invalid".

FIG. 5 shows an example of the flow of address translation.

This figure does not show the protective field flaws. As shown in the figure, the type field is used to determine whether or not to redraw the descriptor after reading it. In the case of redrawing, address conversion is performed again using the address field as a logical address. If it is not redrawing, the main memory is accessed using the address field as a physical address.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to precisely control the sharing of space, and even if the address of the shared light changes due to ejection from main memory to a file, or import from a file, the description on the descriptor is not changed in any way. This can be done without any changes.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an embodiment in which user space is viewed from system space.
FIG. 3 is an explanatory diagram showing an example of data sharing between user spaces,
FIG. 4 is an explanatory diagram showing an example of a descriptor, and FIG. 5 is a flow diagram showing an example of address conversion C11eu. ■...Valid flag, Type...Type field, Addr...Address field, Prot...
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Claims (1)

[Claims] 1. In an address translation method that has an address translation table that defines one or more virtual address spaces and performs translation from a logical address to a physical address, at least a translation table is included in a descriptor of the translation table. An address translation method that has a flag or code that can indicate that redirection is to be performed. 2. The address conversion method according to item 1, wherein the descriptor further includes at least a portion of a logical address used for redrawing. 3. A first device having a means for directly or indirectly indicating in the descriptor which conversion table is used for redrawing.
2. Address conversion method described in Section 2. 4. Have an access protection field in the descriptor, and perform access protection so that access is possible only when both the access protection fields of the descriptor that specifies redirection and the descriptor to which redirection is to be redirected both permit access. The address conversion method according to any one of items 1 to 3, characterized in that: 5. When the descriptor has an access protection field and access protection is performed only by the access protection field of the redrawing source descriptor, or when the access protection fields of both the redrawing source and the redrawing destination permit it. Items 1 to 3, characterized in that it is possible to select whether to perform access protection so that only the user can access
Address translation method described in section.